Residual magnetic devices and methods

ABSTRACT

Residual magnetic locks, brakes, rotation inhibitors, clutches, actuators, and latches. The residual magnetic devices can include a core housing and an armature. The residual magnetic devices can include a coil that receives a magnetization current to create an irreversible residual magnetic force between the core housing and the armature.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Application No.11/094,801, filed Mar. 30, 2005, now U.S. Pat. No. 8,403,124, the entirecontent of which is hereby incorporated by reference.

BACKGROUND

Residual magnetism occurs in materials that acquire magnetic propertieswhen placed in a magnetic field and retain magnetic properties even whenremoved from the magnetic field. Residual magnets are often created byplacing steel, iron, nickel, cobalt, or other soft magnetic materials ina magnetic field. The magnetic field is often generated by runningcurrent through a coil of wire placed proximate to the material. Themagnetic field generated by the coil orders and aligns the magneticdomains in the material, which is a building block for magneticproperties. Once the material is magnetized and the magnetic field isremoved, the magnetic domains remain ordered, and thus, the materialretains its magnetism. The magnetization retained in the material afterthe magnetic field is removed is called the residual or remanence of thematerial, which depends on the properties of the applied magnetic fieldand the properties of the material being magnetized. Residual magnetscan be considered to be irreversible or reversible, depending on howeasily the material can be demagnetized. The residual field of apermanent magnet cannot be easily demagnetized by applying a magneticfield. After a magnetic field is applied to a permanent magnet and thenremoved, the residual field of the permanent magnet will fully restoreitself. Therefore, a permanent magnet is a reversible magnet. Anirreversible magnet, also referred to as a residual magnet or atemporary permanent magnet, requires the form of a closed magnetic path(e.g., a ring) in order to set and maintain a residual magnetic field.The residual magnetic field is set by applying a magnetic field to theirreversible magnet. However, the residual magnetic field remains afterthe magnetic field is removed. The irreversible residual magnet caneasily be demagnetized by a magnetic field. After a magnetic field isapplied to the residual magnet and then removed, the residual field willnot restore itself like the permanent magnet. Therefore, a residualmagnet is an irreversible magnet. The irreversible residual magnet willalso lose its residual field if its closed magnetic path is opened. Evenwhen the magnetic path is closed again, the residual field of theirreversible residual magnet will not restore itself. Magnetic air gapscan exist to a certain size as part of the closed magnetic path of anirreversible residual magnet and still provide a useful amount ofresidual magnetic load. The smaller the magnetic air gap, the closer theresidual load approaches that of an uninterrupted or completely closedmagnet path. Herein, the residual magnetic devices described shall beconsidered irreversible residual magnets, as defined above.

SUMMARY OF THE INVENTION

Some embodiments of the invention provide a solution to retaining anarmature engaged with a core housing without requiring current or power.Using a residual magnetic force, power can be provided to change thestate of the armature and the core housing from an engaged state to adisengaged state, and a residual magnetic force can retain the state ofthe armature and the core housing without requiring power. In addition,some embodiments of the invention can release or disengage the armaturefrom the core housing by providing a manual release mechanism. Themanual release mechanism can increase a separation distance between thearmature and the core housing that substantially nulls the residualmagnetic force retaining the armature engaged with the core housing.

Some embodiments of the invention provide residual magnetic locks,brakes, rotation blocking devices, clutches, actuators, and latches. Theresidual magnetic devices can include a core housing and an armature.The residual magnetic devices can include a coil that receives amagnetization current to create an irreversible residual magnetic forcebetween the core housing and the armature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a residual magnetic device according to oneembodiment of the invention.

FIG. 2 illustrates a core housing for a residual magnetic device.

FIG. 3 schematically illustrates a controller for the residual magneticdevice of FIG. 1.

FIG. 4 schematically illustrates a microcontroller of the controller ofFIG. 3.

FIG. 5 is a cross-section view of an electromagnetic assembly accordingto one embodiment of the invention.

FIGS. 6a-6h are magnetic hysteresis curve graphs for various materialcharacteristics.

FIG. 7 is a demagnetization quadrant of the hysteresis curve graph ofFIG. 6 g.

FIGS. 8 and 9 are side views of a rotation blocking system with aresidual magnetic device according to one embodiment of the invention.

FIG. 10 is a side view of a rotation blocking system with a residualmagnetic locking device with a break-over mechanism according to oneembodiment of the invention.

FIG. 11 is a perspective view of a rotation blocking system with aresidual magnetic device according to another embodiment of theinvention.

FIG. 12 is an exploded view of the rotation blocking system of FIG. 11.

FIGS. 13 and 14 are front views of an armature of the rotation blockingsystem of FIG. 12.

FIG. 15 is a cross-sectional view of the rotation blocking system ofFIG. 11 in an unlocked state.

FIG. 16 is a cross-sectional view of the rotation blocking system ofFIG. 11 in a locked stated.

FIG. 17 illustrates a tire braking system with a residual magneticdevice according to one embodiment of the invention.

FIG. 18 illustrates a cylindrically-shaped residual magnetic deviceaccording to one embodiment of the invention.

FIG. 19 illustrates a U-shaped residual magnetic device according to oneembodiment of the invention.

FIG. 20 is a cross-sectional view of the cylindrical-shaped residualmagnetic device of FIG. 18 and the resulting magnetic field according toone embodiment of the invention.

FIG. 21 is a cross-sectional view of the U-shaped residual magneticdevice of FIG. 19 and the resulting magnetic field according to oneembodiment of the invention.

FIG. 22 illustrates a pivoting residual magnetic axial latch in anengaged state according to one embodiment of the invention.

FIG. 23 illustrates the pivoting residual magnetic axial latch of FIG.22 in a disengaged state.

FIG. 24 illustrates a pivoting residual magnetic axial latch in anengaged state according to one embodiment of the invention.

FIG. 25 illustrates the pivoting residual magnetic axial latch of FIG.24 in an engaged state.

FIG. 26 illustrates the pivoting residual magnetic axial latch of FIG.24 in a disengaged state.

FIG. 27 illustrates a non-integrated pivoting residual magnetic axiallatch in an engaged state according to one embodiment of the invention.

FIG. 28 illustrates the non-integrated pivoting residual magnetic axiallatch of FIG. 27 in a disengaged state.

FIG. 29 illustrates the non-integrated pivoting residual magnetic axiallatch of FIG. 27 in an engaged state.

FIG. 30 illustrates a non-integrated pivoting residual magnetic axiallatch in an engaged state according to another embodiment of theinvention.

FIG. 31 illustrates the non-integrated pivoting residual magnetic axiallatch of FIG. 30 in a disengaged state.

FIG. 32 illustrates the non-integrated pivoting residual magnetic axiallatch of FIG. 30 in an engaged state.

FIG. 33 illustrates another non-integrated pivoting residual magneticaxial latch in an engaged state according to an embodiment of theinvention.

FIG. 34 illustrates the non-integrated pivoting residual magnetic axiallatch of FIG. 33 in a disengaged state.

FIG. 35 illustrates the non-integrated pivoting residual magnetic axiallatch of the FIG. 33 in an engaged state.

FIG. 36 schematically illustrates a clutch system with a residualmagnetic device in a disengaged state according to one embodiment of theinvention, and FIG. 36A illustrates a partially sectioned clutch systemof FIG. 36, shown in a steering column lock application and in adisengaged state.

FIG. 37 schematically illustrates the clutch system of FIG. 36 in anengaged state, and FIG. 37A illustrates the partially sectioned clutchsystem of FIG. 36A, shown in an engaged state.

FIG. 38 illustrates a variable reluctance rotary torque actuator with aresidual magnetic latch according to one embodiment of the invention.

FIG. 39 illustrates the rotary torque actuator of FIG. 38 as theresidual magnetic latch is being engaged.

FIG. 40 illustrates the rotary torque actuator of FIG. 38 in an engagedstate.

FIG. 41 illustrates the rotary torque actuator of FIG. 40 as theresidual magnetic device is being disengaged.

FIG. 42 illustrates a variable reluctance rotary torque actuator with aresidual magnetic latch in an engaged state under the influence of adoor handle force according to one embodiment of the invention.

FIG. 43 illustrates the rotary torque actuator of FIG. 42 under theinfluence of a door handle force with the residual magnetic latch in adisengaged state.

FIG. 44 illustrates a front view of a gear-driven latch system withresidual magnetic device in an engaged state according to one embodimentof the invention.

FIG. 45 illustrates a cross-sectional view of the gear-driven latchsystem of FIG. 44 with the residual magnetic device in an engaged state.

FIG. 46 illustrates a cross-sectional view of the gear-driven latchsystem of FIG. 44 with the residual magnetic device in a disengagedstate.

FIG. 47 illustrates a front view of the gear-driven latch system of FIG.44 with the residual magnetic device in a disengaged state.

FIG. 48 illustrates a front view of a linkage latch system with aresidual magnetic device in a disengaged state according to oneembodiment of the invention.

FIG. 49 illustrates the linkage latch system of FIG. 48 with theresidual magnetic device in an engaged state.

FIG. 50 illustrates a front view of a linkage latch system with aresidual magnetic device in an engaged state according to one embodimentof the invention.

FIG. 51 illustrates a front view of the linkage latch system of FIG. 50with the residual magnetic device in a disengaged state.

FIG. 52 illustrates a front view of the linkage latch system of FIG. 50with the residual magnetic device is a reset engaged state.

FIG. 53 illustrates a cross-sectional view of the linkage latch systemof FIG. 50 with the residual magnetic device in an engaged state.

FIG. 54 illustrates a cross-sectional view of the linkage latch systemof FIG. 50 with the residual magnetic device in a disengaged state.

FIG. 55 illustrates a front view of an integrated latch system with aresidual magnetic device.

FIG. 56 illustrates a cross-sectional view of the latch system of FIG.55.

FIG. 57 illustrates a wrap spring device with a residual magnetic deviceaccording to one embodiment of the invention.

FIG. 58 illustrates a front view of the wrap spring device of FIG. 57.

FIG. 59 illustrates a cross-sectional view of the wrap spring device ofFIG. 57.

FIG. 60 illustrates a cross-sectional view of a cam clutch/brake devicewith a residual magnetic device according to one embodiment of theinvention.

FIG. 61 is a perspective view of a vehicle that can include one or moreembodiments of the residual magnetic devices of FIGS. 1-60.

FIG. 62 is a schematic view of a building including doors and/or windowslocked with one or more embodiments of the residual magnetic devices ofFIGS. 1-60.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limited. The use of“including,” “comprising” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. The terms “mounted,” “connected” and“coupled” are used broadly and encompass both direct and indirectmounting, connecting and coupling. Further, “connected” and “coupled”are not restricted to physical or mechanical connections or couplings,and can include electrical connections or couplings, whether direct orindirect.

In addition, embodiments of the invention include both hardware andelectronic components or modules that, for purposes of discussion, maybe illustrated and described as if the majority of the components wereimplemented solely in hardware. However, one of ordinary skill in theart, and based on a reading of this detailed description, wouldrecognize that, in at least one embodiment, the electronic based aspectsof the invention may be implemented in software. As such, it should benoted that a plurality of hardware and software based devices, as wellas a plurality of different structural components may be utilized toimplement the invention. Furthermore, and as described in subsequentparagraphs, the specific mechanical configurations illustrated in thedrawings are intended to exemplify embodiments of the invention and thatother alternative mechanical configurations are possible.

FIG. 1 illustrates an application of residual magnetic technology toblock the rotation of a device using a residual magnetic device 10according to one embodiment of the invention. The residual magneticdevice 10 includes a steering column lock 12 that can block the rotationof a steering wheel 14 or a steering yoke in a vehicle 16. In someembodiments, the steering column lock 12 can also be used to block therotation of a handlebar on a bicycle or motorcycle. The steering columnlock 12 includes an armature 18, a core housing 20, a coil 22, and acontroller 24. The armature 18, the core housing 20, and the coil 22form an electromagnetic assembly 26. The electromagnetic assembly 26 canbe used in other applications besides the steering column lock 12, asshown and described with respect to FIGS. 8-60. The materials, control,and construction of the electromagnetic assembly 26 as described hereinalso applies to the embodiments shown and described with respect toFIGS. 8-60.

The steering column lock 12 can also include a biasing member 27 thatapplies a load or force to separate the armature 18 and the core housing20. The biasing member 27 can include one or more compression springs,tension springs, elastomeric members, wedges, and/or foams.

The magnetic closed path structure formed by the armature 18 and thecore housing 20 is constructed from a material that acquires magneticproperties when placed in a magnetic field and retains magneticproperties after the magnetic field is removed. In some embodiments, thearmature 18 and the core housing 20 are constructed of SAE 52100 alloyedsteel having a hardness of approximately 40 Rc, which can developcoercive forces H_(C) of 20 to 25 Oersteds and residual magnetic fluxdensities B_(R) as high as 13,000 Gauss when constructed with a closedmagnetic path (e.g., a ring) and is exposed to a certain level ofmagnetic field. The armature 18 and the core housing 20 can also beconstructed from other materials, such as various steel alloys, SAE 1002steel, SAE 1018 steel, SAE 1044 steel, SAE 1060 steel, SAE 1075 steel,SAE 1080, SAE 52100 steel, various chromium steels, various tool steels,air hardenable (or A2) tool steel. One or more portions of the armatureand the core housing (e.g., hard outer layers and soft inner portions)can have various hardness values, such as 20 Rc, 40 Rc, and 60 Rc. Mostsoft magnetic material displays a certain amount of residual or remanentmagnetism (flux density). The coercive force (H axis) and residual fluxdensity (B axis) determine whether the residual magnetic device 10 isappropriate for a particular application. In some embodiments, coerciveforce and flux density can vary. The greater the magnetic flux producedat the air gap and the magnetomotive force it maintains across the airgap, the greater the residual magnetic force will be for the residualmagnetic device. The coercive forces can vary from 1.5 Oersteds for asoft, low-carbon steel (e.g., SAE 1002) to 53 Oersteds for ahighly-alloyed steel (e.g., SAE 52100 with a hardness of 60 Rc). Otherranges of coercive forces and/or hardness values may be suitable forparticular applications. Additional materials and related residualmagnetic properties will be described below.

Generally, the higher the magnetic flux (Maxwells) and the magnetomotiveforce (Amp-Turns) that can be maintained across a given magnetic airgap, the less dependence on the size of the magnetic air gap. Forexample, the armature 18 and the core housing 20 are engaged when thearmature 18 and the core housing 20 are magnetized by the magnetic fieldgenerated from the coil 22. The higher the coercive force and the fluxdensity of the material of the armature 18 and the core housing 20, thestronger the engaging force between the armature 18 and the core housing20. A large coercive force and a large flux density also provideincreased tolerance with respect to separations or gaps between thecomponents, while still providing an effective locking or braking forcefor a particular application. For example, components constructed ofmaterial with a high coercive force and a high flux density can beseparated by a larger air gap and still provide the same residual forceas components constructed of material with a low coercive force and alow flux density separated by a smaller air gap.

The material of the armature 18 and the core housing 20 can also bevaried to change the weight and/or size of the steering column lock 12or any other type of residual magnetic device. Whether the type ofmaterial can reduce the size and weight of the residual magnetic lock isdependant on the residual properties of the material B_(R) and H_(C).The higher the energy at the air gap provided by the material, thesmaller the residual magnetic device can be. The size of the residualmagnetic device can vary to accommodate weight requirements of specificapplications. For example, some vehicles have weight and/or sizerestrictions that limit the dimensions and/or weight of the steeringcolumn lock 12. In some embodiments, the armature 18 and the corehousing 20 are constructed of SAE 52100 with a hardness of 40 Rc, andthe armature 18 and the core housing 20 together can weigh up toapproximately 10 pounds. Other types of materials and hardness valuescan also be used in the steering column lock 12 to increase or decreasethe size and/or weight of the steering column lock 12.

As shown in FIGS. 2 and 5, the core housing 20 includes an inner core 20a, an outer core 20 b, and a yoke 20 c (which supports the inner andouter cores), and a recession or opening 20 d located between the innercore 20 a and the outer core 20 b. The recession 20 d holds the coil 22.In some embodiments, the coil 22 includes 21 gauge copper wiring. Otherconductive wiring or mediums can also be included in the coil 22. Thecurrent supplied and the number of turns in the coil 22 determines themagnetic field and flux applied to the material of the armature 18 andcore housing 20 and the corresponding engaging force between thearmature 18 and the core housing 20. In some embodiments, the coil 22includes 265 turns, although fewer or more turns could be used dependingon the specific application of the lock 12 and the current levelsachievable.

The coil 22 is coupled to the controller 24. In some embodiments, thecontroller 24 does not include a microprocessor, but rather can includeas few components as one or more sensors, one or more switches, and/oran analog circuit of discrete components. In some embodiments, thecontroller 24 can include one or more integrated circuits orprogrammable logic controllers. FIGS. 3 and 4 illustrate one embodimentof the controller 24. The controller 24 can include a microcontroller28, a state determination port module 29, hardware interlock circuitry32, a power supply control module 34, a power supply 35, a bustransceiver 36, and an internal bus or connection mechanism 37 that canconnect all or a subset of the components of the microcontroller 28. Insome embodiments, the bus transceiver 36 provides serial communicationwith other control systems included in a network, such as a localinterconnect network (“LIN”) or a controller area network (“CAN”) thatis traditionally used to connect vehicular control systems. The bustransceiver 36 can provide and receive status and control information toand from other vehicular control systems over the network.

The bus transceiver 36 can also provide and receive status and controlinformation to and from the internal bus 37 of the controller 24. Forexample, the bus transceiver 36 can receive a control signal to lock orunlock the steering column lock 12 and can transmit the control signalto the microcontroller 28. The microcontroller 28 can process thecontrol signal and transmit one or more control signals to the powersupply 35 and/or the power supply control module 34. The power supply 35can generate a magnetization or demagnetization current that will engageor disengage the armature 18 and the core housing 20 in order to lock orunlock the steering column lock 12. In some embodiments, the controller24 can receive power from an external power supply (e.g., an ignitionsystem) rather than including a separate power supply 35. The powersupply 35 can also include a chemical or stored energy system, forexample, a battery. In one embodiment, the power supply 35 can begenerated by a user by spinning or otherwise moving a portion of agenerator to create enough energy to supply a magnetization ordemagnetization current to the coil 22. A piezoelectric device can alsobe used as a human-initiated power supply. Using human movement tocreate the power supply 35 for the electromagnetic assembly 26 cansubstantially or completely eliminate the need to include a readilyavailable power source such as a battery, a direct current power source,or an alternating power source with the power supply 35. In otherembodiments, the power supply 35 can include a solar power source, astatic electricity power source, and/or a nuclear power source.

The power supply control module 34 can include an H-bridge integratedcircuit, one or more transistors, or one or more relays that regulatethe level, direction, and duration of the current applied to the coil22. In some embodiments, the electromagnetic assembly 26 can include asingle coil 22 and the power supply control module 34 can include anH-bridge integrated circuit, four transistors, or relays to provide abipolar current drive circuit that provides forward and reverse polaritycurrent to the coil 22. In other embodiments, the electromagneticassembly 26 can include two coils 22 and the power supply control module34 can include two transistors to provide two unipolar drive circuits.One unipolar drive circuit can provide a first current to one of thecoils 22 and the other unipolar drive circuit can provide a secondcurrent, opposite in polarity to the first current, to the other coil22.

In some embodiments, the state determination port 29 of the controller24 can send and receive signals to determine the state of theelectromagnetic assembly 26 (e.g., whether or not a residual magneticforce is present between the armature 18 and the core housing 20, suchthat the components are engaged or disengaged). The state of theelectromagnetic assembly 26 can be used to control the lock 12. Forexample, the biasing member 27 can apply a biasing force that separatesor disengages the armature 18 from the core housing 20, and the state ofthe electromagnetic assembly 26 can be used to determine when to applythe biasing force. The state of the electromagnetic assembly 26 can alsobe used to ensure that a demagnetization current is only applied when acorresponding magnetization current has previously been applied toprotect the electromagnetic assembly 26 from damage or undesiredoperation.

In some embodiments, the controller 24 determines the state of theelectromagnetic assembly 26 by determining the inductance of theelectromagnetic assembly 26. Referring to FIG. 5, the inductance of theelectromagnetic assembly 26 changes as a function of a magnetic air gap60 between the armature 18 and the core housing 20. For example, withthe armature 18 in substantial contact with the core housing 20, theinductance of the electromagnetic assembly 26 is approximately threetimes greater than the inductance of the electromagnet assembly 26 whenthe armature 18 is separated from the core housing 20 by approximately 1millimeter. To determine the inductance of the electromagnetic assembly26, the controller 24 can send a voltage pulse to the coil 22 and thestate determination port 29 can measure the current rise. In someembodiments, the controller 24 can generate a voltage pulseapproximately every 50 microseconds and measure the current rise in theelectromagnetic assembly 26. When the armature 18 is substantially incontact with the core housing 20, the current rise is greater than thecurrent rise when the armature 18 and the core housing 20 are separated(due to the resistance created by air between the components).Separation distances can be categorized as either a separation distancepresent when the lock 12 is engaged (due to the surfaces of the armature18 and the core housing 20 not being perfectly smooth) or as aseparation distance present when the armature 18 and core housing 20 aredisengaged. A threshold separation distance (e.g., one or severalmillimeters) can divide the two categories of separation distances. Thecontroller 24 can compute a separation distance based on the observedcurrent rise and can compare the computed separation distance to thethreshold separation distance to determine the state of theelectromagnetic assembly 26.

The state determination port 29 of the controller 24 can also use othermechanisms for determining the state of the electromagnetic assembly 26.For example, the state determination port 29 can be connected to one ormore sensors, such as a Hall effect sensor that determines at least acharacteristic of the magnetic flux present in the electromagneticassembly 26. A Hall effect sensor placed in a flux path of theelectromagnetic assembly 26 can sense magnetic flux values and cantransmit flux values to the state determination port 29. The statedetermination port 29 can use the flux values to determine whether thesensed magnetic flux corresponds to a flux present when theelectromagnetic assembly 26 is engaged or disengaged.

The state determination port 29 or the microcontroller 28 of thecontroller 24 can store the current state of the electromagneticassembly 26 and can update the state when it applies a magnetizationcurrent or a demagnetization reverse current. In one embodiment, thecontroller 24 can be configured to apply a precautionary magnetizationcurrent before applying a demagnetization current. The precautionarymagnetization current can ensure that a residual magnetic force ispresent before applying a demagnetization current. The precautionarymagnetization current does not damage the electromagnetic assembly 26,because, in most embodiments, the material of the armature 18 and thecore housing 20 is already at a maximum magnetic saturation. In otherembodiments, the state determination port 29 can monitor mechanicalmechanisms, such as a strain gage, placed between the armature 18 andthe core housing 20 to determine the amount of pressure present betweenthe components and to determine whether the components are engaged ordisengaged. In one embodiment, a mechanical switch that is moved by themovement of the armature 18 can be used to mechanically record the stateof the lock 12. The switch can include, for example, a microswitch, aload pad, a membrane pad, a piezoelectric device, and/or a force-sensingresistor.

In some embodiments, the hardware interlock circuitry 30 of thecontroller 24 can provide safety features to help keep the lock 12 frominadvertently locking or unlocking. For example, the hardware interlockcircuitry 30 can filter control signals received by the bus transceiver36 or generated by the microcontroller 28 to ensure that invalid signalsdo not lock or unlock the lock 12. The hardware interlock circuitry 30can prevent power surges or rapid control signals from unintentionallylocking and/or unlocking the lock 12. Upon detecting an invalid signal,the hardware interlock circuitry 30 can disable operation of the lock 12until the controller 24 is reset or repaired, if necessary. In someembodiments, when power is provided to the controller 24, the hardwareinterlock circuitry 30 can disable operation of the electromagneticassembly 26 until operational checks are performed and passed (e.g.,supplied voltage is within a valid range, an appropriate state of theelectromagnetic assembly 26 is determined, etc.). In one embodiment, thehardware interlock circuitry 30 can be disabled during a set-up phase ofthe controller 24 and can later be initiated and set for operation.

The controller 24 is not limited to the components and modulesillustrated and described above. The functionality provided by thecomponents described above can also be combined in a variety of ways. Insome embodiments, the controller 24 can provide tamper-prooffunctionality, such that unauthorized locking or unlocking of the lock12 cannot be accomplished by modifying the stored state of theelectromagnetic assembly 2 b or the locking and unlocking processprovided by the controller 24.

In some embodiments, as shown in FIG. 4, the microcontroller 28 caninclude a transceiver 40, a state tool module 41, a processor 42, and amemory module 43. The microcontroller 28 can also include more or fewercomponents and the functionality provided by the components listed abovecan also be combined and distributed in a variety of ways. Themicrocontroller 28 can receive and send signals through the transceiver40. In some embodiments, the transceiver 40 includes a universalasynchronous receiver/transmitter that allows the microcontroller 28 toasynchronously receive and transmit control and/or status signals. Thestate tool module 41 can include amplifiers, converters (e.g., an analogto digital converter), or other tools for processing state determinationsignals sent and received over the state determination port 29. Theprocessor 42 can include a microprocessor, an application specificintegrated circuit or other mechanisms for receiving input andprocessing instructions. In some embodiments, the processor 42 can issueinstructions or control signals that are output by the transceiver 40and transmitted to the bus transceiver 36, the power supply 35, thepower supply control module 34, state determination port 29, and/or thehardware interlock circuitry 30. The control signals can be used toreport the state of the electromagnetic assembly 26, change the state ofthe electromagnetic assembly 26, and/or determine the state of theelectromagnetic assembly 26.

The memory module 43 can include non-volatile memory, such as one of orcombinations of ROM, disk drives, and/or RAM. In some embodiments, thememory module 43 includes flash memory. The memory module 43 can includeinstructions and data that has been obtained and/or executed by theprocessor 42. In some embodiments, the memory module 43 can include avariable, flag, register, or bit that designates the state of theelectromagnetic assembly 26. In some embodiments, the memory module 43can store operational information regarding the components of thecontroller 24. For example, the memory module 43 can store a range ofvoltage values that the power supply control module 34 can provide, thecurrent state of the hardware interlock circuitry 30, threshold data forcomparison against data received on the state determination port 29,etc.

In some embodiments, the controller 24 can supply voltage to the coil 22to generate or eliminate a residual magnetic force between the armature18 and the core housing 22. The voltage supplied by the controller 24can range from approximately 8 Volts to approximately 24 Volts. Otherspecific voltages and ranges of voltages can also be used depending onthe properties and particular applications. In some embodiments, thecontroller 24 can supply a magnetization current of up to approximately10 Amps to the coil 22 that creates a magnetic field around the coil 22.The magnetic field created by the magnetization current applied to thecoil 22 can create a residual magnetic force between the armature 18 andthe core housing 20 that draws and holds the armature 18 to the corehousing 20, even when the controller stops supplying the magnetizationcurrent.

The controller 24 can also supply a demagnetization current to the coil22. The demagnetization current can have a polarity substantiallyopposite to the magnetization current and a current of up toapproximately 2 Amps. Other demagnetization current levels can also beused. The demagnetization current can create a magnetic field around thecoil 22 in an opposite direction as the field generated by themagnetization current. The opposite direction of the magnetic fieldgenerated by the demagnetization current balances or nullifies thedirection of magnetic field previously-generated with the magnetizationcurrent to substantially eliminate the residual magnetic force betweenthe armature 18 and the core housing 20. As previously described, insome embodiments, the electromagnetic assembly can include a single coil22 and the controller 24 can include a bipolar drive circuit, such as anH-bridge integrated circuit or four transistors that provides themagnetization current and the demagnetization current to the coil 22.Alternatively, the electromagnetic assembly 26 can include two coils 22and the controller 24 can include two drive circuits, each with twotransistors. One of the drive circuits can provide the magnetizationcurrent to one coil 22 and the other drive circuit can provide thedemagnetization current to the other coil 22.

During the demagnetization process, the controller 24 can applyalternate polarity currents (i.e., magnetization and demagnetizationcurrents) in pulses that can, in some embodiments, decrease in durationto create a gradually-decreasing magnetic field. By decreasing theduration of each of the alternating polarity pulses, current levels inthe coil 22, and thus, magnetic flux levels in the core housing 20 cangradually decrease until the hysteresis of the core housing 20 isminimal.

In some embodiments, the controller 24 can use pulse width modulation(“PWM”) to provide an increasing demagnetization current to the coil 22until the residual force of the core housing 20 is nullified. In someembodiments, the controller 24 can continue to apply an increasingdemagnetization current to the coil 22 until a mechanism (e.g., a springor other mechanical device) physically releases the armature 18 from thecore housing 20. The controller 24 can sense the physical release of thearmature 18 from the core housing 20 and can determine that a releasepoint has been met and the demagnetization current is no longer needed.The release point can be where the residual force between the armature18 and the core housing 20 is at or below a threshold where the armature18 and core housing 20 are considered disengaged. In some embodiments,the controller 24 may not have established a release point for thearmature 18 and core housing 20 before applying a demagnetizationcurrent. The controller 24 can use PWM to reach a release point.

Alternatively, in some embodiments, the controller 24 has previouslyestablished or been provided with a release point for theelectromagnetic assembly 26 and can apply a calibrated pulsed widthmodulated power signal based on the supply voltage. The release pointcan have a tolerance of approximately 10%. The controller 24 can use theestablished release point along with the tolerance to determine anominal release current. The controller 24 can apply a pulse widthmodulated power signal whose duty cycle is based on the supply voltagelevel supplied by the controller 24.

Also, because residual magnets are irreversible magnets, breaking theclosed magnetic path or increasing an air gap between the armature 18and the core housing 20 with a manual release mechanism 47 can cancel orneutralize the residual magnetism. In some embodiments, the ability tophysically or manually release the armature 18 from the core housing 20can provide a safety mechanism to unlock or disengage the lock insituations where a demagnetizing current cannot be provided (e.g., apower loss). The steering column 12 can include a manual releasemechanism 47 that includes a jack screw (as shown in FIG. 5) placed onthe armature 18, and the steering column 12 can be manually unlocked byscrewing or turning the screw into the armature 18 until the screw makescontact with core housing 18 and separates the armature 18 and the corehousing 20. Additional residual magnetic devices can also include manualrelease mechanisms 47 that include remote release mechanisms. Forexample, a cam or a wedge and an accessible lever or cable can be usedto a manually release a trunk latch by operating the lever or cable toload the cam or wedge against an armature to create the separationnecessary to neutralize the magnetic load.

Referring to FIG. 1 and the steering column lock 12, the core housing 20and the coil 22 can be mounted firmly to the vehicle 16. The corehousing 20 and the coil 22 can be mounted concentric with a steeringwheel shaft 48. In some embodiments, the center axis of the core housing20 and/or the coil 22 can be mounted off-center to the center axis ofthe steering wheel. The armature 18 can be rotateably constrained to thesteering wheel shaft 48, but can move in the axial direction of thesteering wheel shaft 48. The armature 18 can be mounted concentric withthe steering wheel shaft 48. The center axis of the armature 18 can alsobe mounted off-center to the center axis of the steering wheel shaft 48.In some embodiments, gears, linkages, or other suitable components canbe used to couple the armature and/or the core housing to the steeringwheel shaft 48.

When voltage is applied to the coil 22 by the controller 24, a currentdraw occurs that is proportional to the electrical resistance of thecoil 22. The current and the number of windings of the coil 20 determinethe magnetic flux applied to the material of the core housing 20 and thearmature 18. The magnetic flux applied to the material of the corehousing 20 and the armature 18 can generate a normal (i.e.,perpendicular to the surfaces of the core housing 20 and the armature18) magnetic force between the core housing 20 and the armature 18. Theamount of magnetic flux generated by the coil 22 and the flux densitystate of the material (i.e., whether the material is fully saturated)can determine the strength of the residual magnetic force between thecore housing 20 and the armature 18. The air gap between the corehousing 20 and the armature 18 can also influence the strength of theresidual magnetic force between the core housing 20 and the armature 18.

In some embodiments, the magnetic flux levels in the materials and,subsequently, the residual magnetic force between the core housing 20and the armature 18 increases until magnetic saturation of the corehousing 20 and the armature 18 is reached. Magnetic saturation occurswhen a material has reached its maximum magnetic potential. In someembodiments, the controller 24 provides current for approximately 50milliseconds to approximately 100 milliseconds to bring the armature 18and the core housing 20 to magnetic saturation. Once magnetic saturationis reached, further application of current adds little or nothing to theattractive or residual magnetic force of the material.

FIG. 5 illustrates a cross-sectional view of the armature 18, the corehousing 20, and the coil 22, each of which is located concentric to thesteering wheel shaft 48. In some embodiments, a first cross-sectionalarea 50 of the armature 18, a second cross-sectional area 51 the outercore 20 b, a third cross-sectional area 55 of the inner core 20 a, and afourth cross-sectional area 57 of the yoke 20 c are substantially equalin order to increase the probability that the core housing 2 andarmature 18 reach magnetic saturation at approximately the same time. Insome embodiments, reaching high or maximum saturation levels and allcomponents reaching the levels at the same time can provide an optimalresidual force. For example, magnetic saturation can provide apredetermined residual force that requires a predetermineddemagnetization current for canceling the generated residual force. Ifone or both of the armature 18 and the core housing 20 are not broughtto full magnetic saturation, the amount of demagnetization currentneeded to reverse the residual force can be more difficult to determine.

Once the desired residual magnetic force is created between the armature18 and the core housing 20, the armature 18 and the core housing 20 areengaged and the steering wheel is locked by the steering column lock 12.The steering wheel 14 can be substantially blocked from rotating becausethe core housing 20 is mounted to the vehicle 16 such that the corehousing 20 cannot rotate or move. The armature 18, which previouslyrotated with the steering wheel 14 before being residually magnetized,is held to the core housing 20 by the residual magnetic force generatedbetween the armature 18 and the core housing 20.

Due to the hysteretic property of magnetic material, the controller 24can stop supplying the magnetization current to the coil 22 once thelock 12 is engaged. In some embodiments, the hysteretic property ofmagnetic material limits the amount of power needed by the lock 12because the controller 24 only supplies power to change the state of thelock 12, not to retain the state of the lock 12.

The optimum magnitude of the residual magnetic force created by theapplication of the voltage to the coil 22 can be determined with thecross-sectional areas of the core housing 20 and the armature 18 and bythe magnetic air gap 60 (as shown in FIG. 5) between the armature 18 andthe core housing 20. The smaller the magnetic air gap 60, the closer theelectromagnetic assembly 26 comes to reaching the maximum residual forcefor the material being used. The highest residual force would beobserved without any magnetic air gap 60 when the armature 18 and thecore housing 20 are one integrated part or piece (e.g., a ring ofmaterial with a closed magnetic path).

In certain embodiments, the properties of magnetic material needed tooptimize residual magnetic load are high coercive force (H_(C)) and highresidual flux density (B_(R)). The usefulness of residual magnetic loadis measure by the quantity of flux (Maxwells) it can produce in themagnetic air gap, and the magnetomotive force (Amp-Turns) it canmaintain across the magnetic air gap. One half times the area of thesetwo quantities [½*(Total Air Gap Flux)*(Magnetomotive Force)], or thearea under the air gap permeability line and the hysteresis curve (asshown in FIG. 6g ), is the energy stored in the magnetic air gap. Anoptimum or maximum possible energy of the magnetic air gap per cubiccentimeters of material is, therefore, a logical way to evaluate themagnetic efficiency of the material that will be used in a residualmagnetic application.

FIGS. 6a-6h illustrate magnetic hysteresis curves or loops for severalmaterials, such as steel, with carbon contents from 0.02% to 1.0% andhardnesses from fully annealed to 60 Rc. The curves are divided intofour quadrants. The second quadrant represents the demagnetizingquadrant. The portion of the hysteresis loop included in the secondquadrant is called the demagnetization curve. The residual flux density(B_(R)) exists in a closed path, such as a ring, and the total coerciveintensity (H_(C)) is the force required to overcome the reluctivity ofthe material to establish a closed path.

The introduction of a magnetic air gap of the same size into all of thegraphs illustrated in FIGS. 6a-6h reduces the flux density from (B_(R))to (B_(d)), thereby reducing the reluctivity in the material from(H_(C)) to (H_(C)−H_(d)) and creating a magnetomotive force in themagnetic air gap equal to (H_(d)*the length of the closed path). Theshaded rectangles, each having an area equal to (B_(d)*H_(d)), willtherefore be equal to twice the energy of the magnetic air gap per unitvolume of material. The optimum point of operation of the magneticmaterial will, therefore, be where the area (B_(d)*H_(d)) is a maximumfor a given magnetic air gap.

FIG. 6g illustrates a magnetic hysteresis curve 68 for SAE 52100 alloyedsteel material with a hardness of 40 Rc. The intersection of a magneticair gap permeance line and the magnetic hysteresis curve for a magneticmaterial under consideration determines the flux density B_(d) and themagnetic intensity H_(d) at the air gap, which is useful to determinethe residual magnetic force of the application being considered. Theresidual force of a magnetized armature 18 and core housing 20 withoutthe magnetic air gap 60 is represented by line 70 located on the y-axis.In some embodiments, the magnetic air gap 60 when the lock 12 is engagedranges from approximately 0.002 inches to 0.005 inches. Lines 72 and 74represent the permeance of two possible air gaps [(Flux/(Amp-Turns)]between an armature and a core housing. In embodiments of the steeringcolumn lock 12, the lines 72 and 74 could represent the permeance of a0.002 inches and a 0.005 inches air gap, respectively. When thecross-sectional areas of the pole faces of a desired design aredetermined, the flux densities can be determined by the intersections ofthe lines 72 and 74, and the material hysteresis curve can be useful incalculating the residual magnetic force. In some embodiments, a 0.002inch magnetic air gap is generated with very smooth or finely-lappedsurfaces (i.e., the smoothness or flatness or the surface is better thanone light band and the surface finish is better than an “as ground”finish). A 0.005 inch magnetic air gap can be generated with flat, “asground” finishes. In some embodiments, the magnetic air gap 60 can bereduced from 0.005 inch to 0.002 inch by lapping the “as ground”surface, which makes the surface more smooth and creates a tighter andcloser engagement between the armature 18 and the core housing 20. Insome embodiments, an air gap or separation distance between the armature18 and the core housing 20 when the lock 12 is disengaged is magnitudesgreater than a magnetic air gap when the lock 12 is engaged. Forexample, a disengaged air gap or separation distance can beapproximately 0.05 inch or more.

FIG. 7 illustrates the demagnetization quadrant of the hysteresis curve68 and converts the flux density (B) to torque and the magneticintensity (II) to electrical current related to the physicalcharacteristics of the electromagnetic assembly 26. FIG. 7 illustratesthe calculated torque loads for SAE 52100 alloyed steel with a hardnessof 40 Rc, and with a zero inch magnetic air gap, an 0.002 inch magneticair gap, and an 0.005 magnetic inch air gap, as indicated by lines 70,72, and 74 respectively.

Table 1 lists several magnetic materials, such as steels, that may beused in various residual magnetic applications. In some embodiments, thematerials are selected for a particular residual magnetic application,such as latching force, response time, magnetic response (permeability),etc. Some requirements may require a tighter latching force but may notrequire quick response time. Other applications may require a lowerlatching force but may require a higher magnetic response(permeability). Table 1 lists the properties of the various steels, andprovides the magnetic air gap energy for each material given aparticular magnetic air gap magnetization curve. A magnetic air gapmagnetization curve has a negative slope that is drawn from the originin the second quadrant and intersects with the material demagnetizationcurve. The intersection determines (B_(d)), (H_(d)), and the energy ofthe magnetic air gap per unit volume of the material.

TABLE 1 Permeability, flux density, coercive force, and magnetic air gapenergy for magnetic materials. B_(R) H_(c) B_(d) H_(d) Magnetic Air GapEnergy Gauss Oersteds Gauss Oersteds (B ^(d) * H_(d)) / 2 Materialμ_(max) line/cm² amp-turn/cm line/cm² amp-turn/cm * (line-amp-turn)/cm³SAE 1002 2,280  8,365 1.77  2,000 1.2   955 SAE 1018   564  7,219 6.83 4,211 3.97  6,652 SAE 1044   622  9,838 7.8  6,966 4.287 11,883 SAE1060   869 11,737 6.34  6,337 5.072 12,789 SAE 1075   376  8,508 11.5 4,694 6.1837 11,546 SAE 52100 Rc 20   549 12,915 14.3 11,740 12.51058,439 SAE 52100 Rc 40   443 13,479 20.124 12,599 14.535 72,865 SAE52100 Rc 60   117  9,342 53.14  8,759 11.81 41,160 * 1 joule = 10⁸line-amp-turns/cm³

As shown in Table 1, SAE 52100 Rc 40 alloyed steel has the highestmagnetic air gap energy for the particular magnetic air gap size. Thehigh magnetic air gap energy suggests that 52100 Rc 40 alloyed steel hasthe highest residual magnetic latching or engaging force among thematerials listed in Table 1. The maximum permeability (μ_(max)) of SAE52100 Rc 40 alloyed steel, however, is at 443, which is lower than someof the other materials listed in Table 1. The lower the permeability,the slower the rate of magnetization. Generally, the residual magneticforce increases and the permeability (magnetization rate) decreases asthe alloying or hardness of a material increases.

When the lock 12 is engaged, the magnetic air gap 60 generally resultsin a continuous residual force, even if the armature 18 slips due to atorque force being applied. Conventional steering column locks include abolt that drops into a channel to lock the steering wheel and aid as ananti-theft device. Remotely-operated control systems are often used incombination with the bolt-and-channel mechanical mechanism and arefairly complex due to various motors, cams, and sensors. The bolt usedin conventional steering column locks could be sheared by brute force orby a back load generated by movement of the tires. Once the bolt wassheared, the steering wheel shaft 48, the lock bolt housing, or the lockbolt itself could be damaged. The sheared bolt could also become lockedin the channel and could permanently lock the steering column until thebolt was removed.

Rather than damaging or permanently locking components of the steeringcolumn, the magnetic air gap 60 enables the lock 12 to provide acontinuous force even if some slip occurs. The slip allowed by themagnetic air gap 60 protects the steering column from being damaged. Thegreater the magnetic air gap 60, the easier it is to produce rotationalslipping. For example, an engaged lock 12 (e.g., constructed of SAE52100 alloyed steel with a hardness of 40 Rc) with a 0.005 inch magneticair gap can begin to experience rotational slip when a torque ofapproximately 50 percent of the highest possible residual force of thelock 12 is exerted on the steering wheel shaft 48. However, an engagedlock 12 (e.g., constructed of SAE 52100 alloyed steel with a hardness of40 Rc) with an 0.002 inch magnetic air gap begins to experiencerotational slipping only after an application of torque equal toapproximately 80 percent of the highest possible residual force of thelock 12 is exerted on the steering wheel shaft 48. In some embodiments,the applied torque required to cause rotational slipping ranges fromapproximately 20 foot pounds to 80 foot pounds, depending on the sizeand material of the armature 18 and the core housing 20 and the size ofthe magnetic air gap 60 when the lock 12 is engaged.

In some embodiments, the core housing 20 and the armature 18 are notbrought to magnetic saturation and, if slippage is detected, theresidual magnetic force between the core housing 20 and the armature 18can be increased by powering an additional magnetization current to thecoil 22. In some embodiments where the material has not saturated fully,the residual magnetic force between the core housing 20 and the armature18 can be increased when slipping is detected. The residual magneticforce can also be increased to a predetermined force, such asapproximately 90 foot pounds. In addition, the residual magnetic forcecan be increased by incrementing or modulating additional levels ofcurrent to the coil until saturation has been reached.

In some embodiments, the core housing 20 and the armature 18 are broughtto magnetic saturation and, if slippage is detected, additional currentis applied to the coil 22 to increase an electromagnetic force (e.g.,doubling the force with SAE 52100 steel at a hardness of 40 Rc) betweenthe core housing 20 and the armature 18. When the additional current isstopped, however, the additional electromagnetic force is not retainedsince the core housing 20 and the armature 18 were already magneticallysaturated, and the prior residual magnetic force remains.

The slipping can cause increased friction between the armature 18 andthe core housing 20. For example, slipping under relatively high forcescan cause the steel surfaces of the core housing 20 and the armature 18to begin to seize up as would most non-lubricated steel surfaces. Inrelatively soft materials, surface galling occurs due to particles ofthe surface material rolling. Surface galling can increase the magneticair gap 60 between the core housing 20 and the armature 18. An increasedair gap or separation distance can cause a loss of residual magneticforce, and thus, a loss of braking or locking force. High alloyedsteels, such as SAE 52100 bearing steel, can provide tough and hardsurfaces that limit the amount of seizing or surface galling between thearmature 18 and the core housing 20.

In some embodiments, the material of the armature 18 and the corehousing 20 can be surface treated to provide an outer shell withincreased hardness. In some embodiments, a thermochemical diffusionprocess, referred to as nitriding, is used to create a nitride shell onthe armature 18 and/or the core housing 20. Nitriding generates asurface composition consisting of a “white layer” or “compound zone,”which is usually only a few micro-inches thick, and an outer, nitrogendiffusion zone, which is often approximately 0.003 inches thick or lessto allow for demagnetization.

In some embodiments, the nitriding process can be performed onfully-annealed SAE 52100 steel with a martensitic structure. Amartensitic structure can be achieved by heat treating the steel andcooling it with a marquench or rapid quench. Creating a martensiticstructure within the steel can increase the hardness of the steel. Forexample, SAE 52100 steel with an original hardness of 20 Rc can have anincreased hardness up to 60 Rc after the heat treatment.

The material can also be prepared for nitriding by grinding the surfacesflat to within a 0.005 inch variance and sandblasting the surface toprovide a clean base for the nitride shell. As described above, theflatter and smoother the surfaces, the smaller the magnetic air gap 60and the greater the residual force between the armature 18 and the corehousing 20. The surfaces of the armature 18 and the core housing 20 canalso be cleaned by sandblasting or other conventional cleaning processesbefore beginning the nitriding process.

During the nitriding process, nitrogen can be introduced to the surfaceof the steel while heating the surface of the steel. In someembodiments, the surface can be heated to approximately 950° F. toapproximately 1,000° F. The nitrogen alters the composition of thesurface and creates a harder outer surface or shell that is moreresistant to wear (i.e., surface galling), corrosion, and temperature.Although the nitrided portions of the armature 18 and the core housing20 have increased hardness, the high temperature used during thenitriding process can lower the overall hardness of the steel. In someembodiments, the nitriding process lowers the hardness of SAE 52100steel with a hardness of approximately 50 Rc to a hardness ofapproximately 40 Rc.

The “white layer” generated during the nitriding process can also helpmitigate any residual magnetic stick after demagnetization. This featureis similar to using a brass shim to prevent armature stick in solenoidapplications. Although the “white layer” generally consists of about 90percent iron and about 10 percent nitrogen and carbon, it provides acleaner release for highly-alloyed steels such as SAE 52100. Thethickness of the diffusion zone also aids the release of thedemagnetized components. In some embodiments, the residual magneticstick increases as the depth of the diffusion zone increases.

To nullify the residual force, or demagnetize the material of thearmature 18 and the core housing 20, a magnetic field or flux is appliedto the material of the armature 18 and core housing 20 in an oppositedirection as previously applied by the magnifying current. To generatean opposite magnetic field the controller 24 can reverse the directionof the current previously sent through the coil 22. The controller 24can apply constant current, a variable and/or a pulsed current inreverse in order to nullify the residual force. In some embodiments,when the armature 18 and the core housing 20 are brought to fullmagnetic saturation, the strength of the residual force is known and thecontroller 24 can generate a demagnetization current to cancel the knownresidual force. However, the residual force can be unknown or variable,and the controller 24 can apply a variable demagnetization current. Insome embodiments, the controller 24 can use sensors to determine if thearmature 18 and/or the core housing 20 are demagnetized and, if not, howmuch additional demagnetization current should be supplied to ensurefull demagnetization.

The material of the armature 18 and the core housing 20 determines thepotential residual magnetic force and, consequently, the demagnetizationcurrent needed to cancel or nullify the residual force. The magnitude ofthe demagnetization current can be determined from a graph including amagnetic hysteresis curve for the material of the armature 18 and thecore housing 20, where the curve crosses the magnetic field intensityaxis (as shown in FIGS. 6 and 7). In some materials, there is a smallamount of residual magnetic recoil after demagnetization. To balance outthis magnetic recoil, additional demagnetization current can be used todrive the residual flux density levels into the third quadrant (as shownin FIG. 6g ), or to slightly negative flux density levels, which willcause the flux to recoil to a zero net. In some embodiments, thedemagnetization current can have a value of approximately 700 milliampsto approximately 800 milliamps applied for approximately 60milliseconds. Once the demagnetization current reaches the levelindicated on the magnetic hysteresis curve graph, the magnetic fieldgenerated by the demagnetization current cancels the magnetic fieldgenerated by the magnetization current and substantially eliminates theresidual magnetic force between the armature 18 and the core housing 20.Once the residual force is canceled, the armature 18 is no longerengaged with the core housing 20 by a residual magnetic force. For thesteering column lock 12, with the armature 18 disengaged from the corehousing 20, the armature 18 is allowed to rotate again with the steeringwheel 14 and steering wheel shaft 48.

In some embodiments, the biasing member 27 aids the release of thearmature 18 from the core housing 20. During the demagnetizationprocess, a force applied by the biasing member 27 can become greaterthan the decreasing residual magnetic force between the armature 18 andthe core housing 20. The biasing member 27 can be used to ensure a cleanrelease between the armature 18 and the core housing 20. The biasingmember 27 can also be used to control the separation of the armature 18and core housing 20 to ensure a quiet or smooth release. The forceapplied by the biasing member 27 can be a constant force that releasesthe armature 18 and core housing 20 once the residual force has beensufficiently reduced or nullified, and thus, has become less than theforce applied by the biasing member 27. Alternatively, the biasingmember 27 can apply a variable releasing force between the armature 18and the core housing 20. The functionality provided by the steeringcolumn lock 12 can be used in keyed or lever systems, key fob systems,and/or keyless systems. The configuration of the steering column lock 12can alternatively be used in door locks and/or latch release systems(i.e., glove box latches, convertible cover latches, middle consolelatches, steering wheel or column locks, gas door latches, fasteners,ball or roller bearings, etc.).

FIGS. 8 and 9 illustrate one embodiment of the invention including arotation blocking system that uses residual magnetism to block rotationof a mechanism at predetermined starting and stopping positions. In someembodiments, a residual magnetic device can use both rotary and axialmovement to maximize torque blocking capabilities. FIGS. 8 and 9illustrate a residual magnetic rotation blocking device 78 included in avehicle ignition assembly 80. In some embodiments, the residual magneticrotation blocking device 78 blocks the rotation of a vehicle ignitionassembly 80. The residual magnetic rotation blocking device 78 can blockthe starting or forward rotation of the vehicle ignition assembly 80 toprevent a vehicle from starting. The residual magnetic rotation blockingdevice 78 can also be used to block the return rotation of the vehicleignition assembly 80 to provide a park interlock function that blocksthe rotation of the vehicle ignition assembly 80 until the vehicle is inpark. The residual magnetic rotation blocking device 78 can be used withkeyed vehicle ignition assemblies 80 (as shown in FIG. 8) where a keycan be inserted and turned to operate the vehicle ignition assembly 80.The residual magnetic rotation blocking device 78 can also be used withvehicle ignition assemblies 80 in which a user turns a knob or presses abutton to operate, rotate, or otherwise actuate the vehicle ignitionassembly 80. The residual magnetic rotation blocking device 78 can alsobe used with other rotational-transfer systems configured to start andstop, open or close, select or deselect, or lock or unlock components.

Conventional vehicle ignition assemblies include a solenoid or otherpower actuators to block rotation. Replacing solenoids or poweractuators with the residual magnetic rotation blocking device 78simplifies vehicle ignition assemblies 80 by having fewer moveable partsthat can be broken or damaged. The residual magnetic rotation blockingdevice 78 also requires less power to change states and requires nopower to maintain state. Additionally, the residual magnetic rotationblocking device 78 offers quick state changes and quiet operation.

The vehicle ignition assembly 80 illustrated in FIGS. 8 and 9 includesan input device 82 (such as a key or a knob), an ignition cylinder 83, adriver 84, an ignition switch 86, and the residual magnetic rotationblocking device 78. The input device 82 can be inserted into orotherwise coupled to the ignition cylinder 83. The ignition cylinder 83is rotatably coupled to the driver 84, and the driver 84 is rotateablycoupled to the ignition switch 86. The input device 82 can be used totransfer rotation to the ignition switch 86 in order to operate avehicle ignition to start the vehicle. In some embodiments, the inputdevice 82, the ignition cylinder 83 and/or the driver 84 can be anintegral unit.

The residual magnetic rotation blocking device 78 includes an armature90, a core housing 92, and a coil (not shown). The residual magneticrotation blocking device 78 can also include a controller (not shown)than supplies voltage to the coil. In some embodiments, theconstructions, properties, and operations of the armature 90, the corehousing 92, the coil, and/or the controller are similar to the armature18, the core housing 20, the coil 22, and the controller 24 describedabove with respect to the steering column lock 12. The armature 90 ofthe residual magnetic rotation blocking device 78 can be mountedconcentric and/or adjacent to the driver 84 and can be rotatably coupledto the driver 84 such that rotation of the driver 84 rotates thearmature 90. Conversely, if the armature 90 is blocked from rotating,the driver 84 will also not be able to rotate.

In some embodiments, the core housing 92 can be mounted to a housing(not shown) of the vehicle ignition assembly 80 that can prevent thecore housing 92 from moving in a rotational or an axial directionrelative to the housing. The ignition cylinder 83, which can rotate withthe driver 84, can pass through the core housing 92 and can be allowedto rotate substantially freely through an opening of the core housing92.

In a locked state, as shown in FIG. 8, the vehicle ignition assembly 80can block rotation due to a residual magnetic force between the armature90 and the core housing 92 of the residual magnetic rotation blockingdevice 78. If an operator attempts to rotate the input device 82 withoutproper authorization, the residual magnetic force between the armature90 and the core housing 92 can prevent rotational motion of the inputdevice 82, and thus, the ignition switch 86.

The residual magnetic rotation blocking device 78 can include a detentconfiguration 96 on the armature 90 and the core housing 92. The detentconfiguration 96 can force the armature 90 to move axially away from thecore housing 92, for example, before significant rotational movement canoccur. The detent configuration 96 can include at least one femalerecess 96 a on the core housing 92 and at least one corresponding maleprotrusion 96 b on the armature 90. Multiple female recesses 96 a and/ormultiple male protrusions 96 b can also be included to indicate one ormore operation settings to the operator as he or she turns the inputdevice 82. For example, the core housing 92 can include an off recess,an accessory recess, and a run recess. The core housing 92 can includethe male protrusions 96 b and the armature can include the correspondingfemale recesses 96 a. The camming action necessary to force theprotrusions out of engagement with the recesses adds to the torsionalbraking action of the residual magnetic rotation blocking device 78. Inother words, the axial residual magnetic force between the armature 90and the coil housing 92 along with the detent configuration 96 increasesthe amount of torque required to forcibly rotate the input device 82.

In some embodiments, the vehicle ignition assembly 80 can include abreak-away mechanism 100 built into the ignition cylinder 83 or inputdevice 82. The break-away mechanism 100 can limit the maximum torquethat can be applied to the input device 82 or the ignition cylinder 83by shearing rather than transferring a particular amount of torque tothe vehicle ignition assembly 80. Since the residual magnetic rotationblocking device 78 has a finite ability to resist torque, the break-awaymechanism 100 can prevent the residual magnetic rotation blocking device78 from failing. In some embodiments, the torque required to shear thebreak-away mechanism 100 can be lower than the maximum torque that theresidual magnetic rotation blocking device 78 can resist. In addition,to prevent the break-away mechanism 100 from breaking unnecessarily, thetorque required to shear the break-away mechanism 100 can be higher thanthe torque generated by an operator's hand in normal use.

The vehicle ignition assembly 80 can include other safety orprecautionary mechanisms to restrict unauthorized rotation. In someembodiments, the ignition cylinder 83 or the input device 82 includes abreak-over mechanism 106, as shown in FIG. 10. When the armature 90 andthe core housing 92 are engaged and the vehicle ignition assembly 80 isin a locked state, excess torque can be dissipated by the break-overmechanism 106. The break-over mechanism 106 can include a separationbreak 107 that creates a gap or break along the rotation transfer pathof the vehicle ignition assembly 80. The separation break 107 caninclude a detent configuration 108 with one or more female recesses 108a and one or more male protrusions 108 b. In some embodiments, the maleprotrusions 108 b can include a free-moving ball bearing or circularcomponent that can rest or engage with the female recesses 108 a. Duringnormal operation, the male protrusions 108 a can engage the femalerecesses 108 a such that they move and rotate together. Torque appliedto the input device 82 when the vehicle ignition assembly 80 is in thelocked state can cause the male protrusions 108 b to disengage from thefemale recesses 108 a. For example, if the male protrusions 108 binclude ball bearings, applying torque can force the ball bearings outof the female recesses 108 a. In some embodiments, the detentconfiguration 108 can become disengaged when approximately 2 foot-poundsof torque is applied to the input device 82 or the ignition cylinder 83.When the vehicle ignition assembly 80 is locked and the detentconfiguration is disengaged, female recesses 108 a can remain stationarywhile the male protrusions 108 b can rotate. The detent configuration108 of the break-over mechanism 106 allow excess torque to be dissipatedby the input device 82 or the ignition cylinder 83 without damaging thevehicle ignition assembly 80 or transferring a force that allowsunauthorized access to or operation of the vehicle. The break-overmechanism 106 can also include a biasing member 109 that can return thedetent configuration 108 to a starting or predetermined position (e.g.,a position where the female recesses 108 a are engaged with the malerecesses 108 b). The biasing member 109 can include one or morecompression springs, tension springs, elastomeric members, wedges,and/or foams.

In the unlocked condition, as shown in FIG. 9, the residual magneticrotation blocking device 78 is demagnetized after proper authorizationis received (i.e., the insertion of an accepted key, the shifting of thevehicle transmission into park, passive identification received by asensor, etc.). The residual magnetic force between the armature 90 andthe core housing 92 is removed and the armature 90 is substantially freeto rotate relative to the core housing 92. The detent configuration 96can also provide a momentary “snap” feel when rotating the vehicleignition assembly 80 from one position to another. The feel from thedetent configuration 96 can be used to indicate to the operator thevarious states of the vehicle ignition assembly 80, such as “Off,”“Accessory,” or “Run.” The vehicle ignition assembly 80 can also includeone or more biasing members 104, such as one or more compressionsprings, tension springs, elastomeric members, wedges, and/or foams,located between the armature 90 and the driver 84 to bias the maleprotrusions 96 b to engage the female recesses 96 a. The biasing member104 can alternatively provide a separation force between the armature 90and the core housing 92 when the residual magnetic rotation blockingdevice 78 is disengaged.

The vehicle ignition assembly 80 includes a controller as described withrespect to the steering column lock 12. The controller can providemagnetization and demagnetization currents to the coil in the corehousing 92 to lock and unlock the vehicle ignition assembly 80. Thecontroller can also determine the state of the residual magneticrotation blocking device 78 using one or more of the methods describedabove with respect to the steering column lock 12 (i.e., a switch, Halleffect sensor, etc.).

The vehicle ignition systems 80 described above provide a locked statein which the armature 90 is engaged with the core housing 92 such thatneither can rotate. In another embodiment, disengaging or uncoupling anarmature and a core housing in order to prevent the transfer ofrotational movement can block rotational motion of a vehicle ignitionsystem. By disengaging an armature and core housing, an input device canbe rotated freely in a locked state preventing transfer of rotation to avehicle ignition system or other component. Allowing free rotation of aninput device can eliminate a need for the break-away mechanism 100 orthe break-over mechanism 106.

FIG. 11 illustrates another vehicle ignition assembly 110 according toone embodiment of the invention. The vehicle ignition assembly 110 caninclude a key head or input device 112, a shaft 114, a core housing 116,a coil 118, and a splined coupler 120. The input device 112 can operateas a handle or mechanism for accessing, rotating, releasing, or openinga component, such as a vehicle ignition system, a door, or a latch. Theshaft 114 can extend from the input device 112 and through a centeropening of the core housing 116. In some embodiments, the constructions,properties, and operations of the core housing 116 and the coil 118 aresimilar to the core housing 20 and the coil 22 described above withrespect to the steering column lock 12. The vehicle ignition assembly110 can also include a controller (not shown) as described above withrespect to the steering column lock 12.

The core housing 116 can be positioned within a center opening of thesplined coupler 120. In some embodiments, the core housing 116 can bemounted to the splined coupler 120 such that the core housing 116 canmove rotationally with the splined coupler 120. The rotation of thesplined coupler 120 can be transferred to drive components such asignition contacts, steering column locks, latch releases, etc. Thefunctionality provided by the vehicle ignition assembly 110 can be usedin keyed or lever systems, key fob systems, and/or keyless systems. Theconfiguration of the vehicle ignition assembly 110 can alternatively beused in door locks and/or latch release systems (i.e., glove boxlatches, convertible cover latches, middle console latches, steeringwheel or column locks, gas door latches, fasteners, ball or rollerbearings, etc.).

FIG. 12 illustrates an exploded view of the vehicle ignition assembly110. The vehicle ignition assembly 110 can include the input device 112,the shaft 114, the core housing 116, the coil 118, an armature 122, andthe splined coupler 120. The input device 112 can be attached to theshaft 114 that extends through the center of the core housing 116 andthe armature 122. In some embodiments, the constructions, properties,and operations of the armature 122 are similar to the armature 18described with respect to the steering column lock 12.

The end of the shaft 114 can include a shaft driver 124 that isconfigured to engage with the armature 118. In some embodiments, thearmature 122 can include a center opening 126 that accepts or receivesthe shaft 114 and the driver 124. The armature 122 can be positionedinside the splined coupler 120, such that when the armature 122 rotates,the splined coupler 120 also rotates. The armature 122 and the splinedcoupler 120 can also be configured to allow the armature 122 to moveaxially within the splined coupler 120 to allow the shaft 114 and theshaft driver 124 to engage with the center opening 126 of the armature122.

In some embodiments, the center opening 126 includes a bow-tie shape asshown in FIGS. 12, 13, and 14. FIG. 13 illustrates the shaft 114, whichcan have a generally cylindrical shape, positioned within the centeropening 126 of the armature 122. The size and shape of the shaft 114 andthe center opening 126 allows the shaft 114 to freely rotate within thecenter opening 126 without transferring rotation to the armature 122.

In contrast, FIG. 14 illustrates the shaft driver 124, which has agenerally rectangular shape, positioned within the center opening 126 ofthe armature 122. The shape and size of the shaft driver 124 engagesopposing edges with the center opening 126 such that the rotation of theshaft driver 124 is transferred to the armature 122, and thus, thesplined coupler 120.

The bow-tie shape of the opening 126 can also provide a degree oferror-correction by engaging the armature 122 even when the shaft driver124 and armature 122 are not completely aligned. In some embodiments,the vehicle ignition assembly 110 can perform access authenticationbefore unlocking. An access controller (not shown) can verify a passiveor mechanical input device 112 before unlocking the vehicle ignitionassembly 110. The bow-tie shape can provide a lost-motion function inorder to provide time for authentication. If an operator rotates theinput device 112 faster than the access controller can perform theauthentication, the operator may have to turn back the input device 112to reengage the shaft driver 124 with the center opening 126 of thearmature 122 before attempting to rotate the input device 112 again. Insome embodiments, the access controller, the shaft 114, the shaft driver124, and the armature 122 are constructed to minimize the authorizationtime and the probability of beating the access controller by introducingsufficient lost motion. A variety of rotary and/or linear lost motiondevices can be used with other embodiments to provide sufficient timefor authentication.

FIG. 15 illustrates a cross-sectional view of the vehicle ignitionassembly 110 (taken along reference line 15 illustrated in FIG. 11) inan unlocked state. In the unlocked stated, the armature 122 isdisengaged with the core housing 116 and is engaged with the shaftdriver 124. Rotating the input device 112 transfers rotation down theshaft 114 to the shaft driver 124 and from the shaft driver 124 to thearmature 122. The armature 122 can be positioned such that the rotationof the armature 122 can be transferred to the splined coupler 120, whichcan drive the ignition system or another system. A biasing member 128can apply a force to the armature 122 that, in the absence of a greaterforce (i.e., a residual magnetic force), keeps the armature 122 engagedwith the shaft driver 124. The biasing member 128 can include one ormore compression springs, tension springs, elastomeric members, wedges,and/or foams. With the armature 122 disengaged with the core housing 116and engaged with the shaft driver 124, a path is created to transferrotation applied to the input device 112 to the splined coupler 120.

FIG. 16 illustrates a cross-sectional view of the vehicle ignitionassembly 110 (taken along reference line 15 shown on FIG. 11) in alocked state. To block access to the vehicle ignition assembly 110, aresidual magnetic force is generated between the core housing 116 andarmature 122 by providing a magnetization current or pulse to the coil118. The resulting residual magnetic force can overcome the biasingforce of the spring 128 and can draw the armature 122 toward the corehousing 116. As the armature 122 is pulled to the core housing 116, thecenter opening 126 can be disengaged from the shaft driver 124. Also,the shaft 114 can become engaged with the center opening 126 of thearmature 122, rather than the shaft driver 124. With the shaft driver124 disengaged from the center opening 126 of the armature 122, rotationis not transferred to the armature 122 or the splined coupler 120 andthe rotation cannot be used to operate or initiate the vehicle ignitionassembly 110.

To unlock the vehicle ignition assembly 110, a demagnetization currentcan be provided or pulsed to the coil 118 to reduce or substantiallyeliminate the residual magnetic force between the core housing 116 andthe armature 122. With the residual magnetic force reduced, the forceprovided by the biasing member 128 can pull the armature 122 back intoengagement with the shaft driver 124. With the shaft driver 124 engagedwithin the center opening 126, rotational movement of the input device112 can be transferred to the armature 122 and the splined coupler 120.

The vehicle ignition assembly 110 described above further includes acontroller as described with respect to the steering column lock 12. Thecontroller can provide magnetization and demagnetization currents to thecoil 118 in order to lock and unlock the vehicle ignition assembly 110.The controller can determine the state of the residual magnetic forceusing one or more of the methods described above with respect to thesteering column lock 12 (i.e., a switch, Hall effect sensor, etc.). Insome embodiments, a steering column block-out device (as shown in FIGS.36A and 37A) can be created using a clutch device similar to the vehicleignition assembly 110.

FIG. 17 illustrates a residual magnetic rotational braking system 140for a tire braking system of a vehicle according to another embodimentof the invention. The rotational braking system 140 can include a corehousing 142 including a coil that is substantially grounded to thevehicle, a rotor-armature 148, a coupler 144 that is integrated to a hub152, and a tire or wheel 154. It should be understood that theconstructions, properties, and operations of the core housing 142, thecoil, and the armature of the rotational braking system 140 can besimilar to the core housing 20, the coil 22, and the armature 18described above for the steering column lock 12. The residual magnetictire braking system 140 can also include a controller as described withrespect to the steering column lock 12.

The tire 154 can be attached to the hub 152 such that the rotationalmovement of rotor-armature 148 can be transferred through the coupler144 to the hub 152 and to the tire 154. The rotation of therotor-armature 148 that is transferred to coupler 144 can be prohibitedby the application of a magnetically induced force between the corehousing 142 and the rotor-armature 148. The rotor-armature 148 can movelinearly toward and contact core housing 142 under magnetic attractionto cause friction. The friction converts the kinetic energy of therotating rotor-armature 148 into thermal energy and stops rotation ofthe rotor-armature 148.

The magnetically induced force of the above rotational braking system140 can be generated by a magnetization current pulsed to the coilincluded in the core housing 142. The initiation of a regulated currentpulse could be associated with a human generated load applied to a leveror a pedal such that the load magnitude would be proportional to themagnetization current pulse. The rate and strength of the magnetizationcurrent provided to the coil can be varied to progressively reduce therotational speed of the rotor-armature 148. Progressively largermagnetization currents can create subsequent larger residual magneticloads until the material in the core housing 142 and the rotor-armature148 is fully saturated.

To release the braking system 140 the polarity of the magnetizationcurrent can be reversed (i.e., a demagnetization current) and applied ata predetermined current level to demagnetize the material of the corehousing 142 and rotor-armature 148. In some embodiments, the brakingsystem 140 can be released in a progressive manner by progressivelyincreasing the reversed polarity current until the full predetermineddemagnetization current level is reached.

The above rotational braking system 140 can also be used as a zero powerresidual magnetic parking brake system. The residual magnetic parkingbrake system 140 can include a controller as described with respect tothe steering column lock 12 to create the braking force. The controllercan provide magnetization and demagnetization currents to the coilwithin the core body to apply and release the rotational braking system140. For example, the residual magnetic parking brake can be engaged bypulsing a regulated magnetizing current level to the coil embedded incore body 142 to create a magnetic field with the capability to fullysaturate the material of the core body and rotor-armature. Once thecurrent pulse is complete, a high residual magnetic force will be setand the parking brake is engaged, there will be no need for furtherelectrical interaction with the residual magnetic parking brake untilthe desired time to release it. The controller can also determine thestate of the residual magnetic force between the armature and the corehousing one or more of the methods described above (i.e., a switch, aHall effect sensor, etc.). To release the above RM parking brake system,a demagnetization current can be pulsed to the coil within the corehousing and the residual magnetic force can be reduced or substantiallyeliminated. A biasing member, such as one or more compression springs,tension springs, elastomeric members, wedges, and/or foams, can be usedto bias the rotor-armature 148 away from the core body 142.

The residual magnetic rotational braking and locking devices describedabove can be used in various systems and applications other than thosedescribed above. For example, residual magnetic braking devices,residual magnetic locking devices, and residual magnetic rotationblocking devices as described above can be used to operate rearcompartment or trunk latches and accessory latches such as fuel fillerdoor latches, glove box latches, and console latches. Residual magneticbraking, locking, and/or rotation blocking devices can also be used tooperate door latches, window latches, hood latches, seat mechanisms(e.g., angular and linear seat and headrest position adjusters), doorchecks, clutch engagement actuators, and steering wheel positionadjusters.

The functionality provided by the rotational braking system 140 can alsobe applied to angular and linear systems. In some embodiments, aresidual magnetic axial latch can include a core housing attached to agenerally stationary element or panel (e.g., a vehicle frame or bodypanel, a door frame, a console or compartment, a trunk frame, a hoodframe, a window frame, a seat, etc.) and an armature attached to amoveable element or panel (e.g., a vehicle entrance door, a fuel fillerdoor, a glove compartment door, a console or storage compartment door, aconvertible roof, spare tire crank, a trunk lid, a rear compartmentdoor, a hood, a window, a headrest, etc.). When a residual magneticforce is created, the armature on the moveable element can be retainedto the core housing on the frame in order to lock the moveable elementto the stationary element. The positions of the core housing and thearmature can be interchanged, such that the core housing is attached tothe moveable element and the armature is attached to the stationaryelement.

As shown in FIG. 18, in some embodiments, a residual magnetic axiallatch or retainer 160 can have a toroidal or cylindrical configuration.The residual magnetic axial latch 160 can include an armature 161, acore housing 162, a coil 163, and a controller 164. The residualmagnetic axial latch 160 can also include a shaft 165 that passesthrough the armature 162 and the core housing 164.

Residual magnetic axial latches can also have a U-shaped configuration.FIG. 19 illustrates a residual magnetic axial latch 170 having aU-shaped configuration that includes an armature 171, a core housing172, a coil 173, and a controller 174. The coil 173 of the U-shapedresidual magnetic axial latch 170 can be wrapped around the base of thecore housing 172, rather than being positioned within a yoke or a recessof the cylindrically-shaped core housing 162 of the cylindrically-shapedaxial latch 160.

The constructions, properties, and operations of the armatures 161 and171, the core housings 162 and 172, the coils 163 and 173, and thecontrollers 164 and 165 of the residual magnetic axial latches 160 and170 can be similar to the core housing 20, the coil 22, and the armature18 described in detail with respect to the steering column lock 12.

As shown in FIG. 20, the cylindrically-shaped armature 161 and thecylindrically-shaped core housing 162 can allow a component, such as theshaft 165, to pass through the armature 161 and the core housing 162.The cylindrical shape of the armature 161 and the core housing 162 cancreate a generally cylindrically-shaped magnetic field 176 configured toengage the cylindrically-shaped armature 161 with thecylindrically-shaped core housing 162.

Alternatively, as shown in FIG. 21, the U-shaped configuration of theresidual magnetic axial latch 170 can create a generally flatter,rectangular-shaped magnetic field 178 configured to engage the linear orrod-shaped armature 171 with the top of the U-shaped core housing 172.

The cylindrically-shaped configuration and the U-shaped configurationscan include an armature with a surface area greater than the interfacingsurface area of a corresponding core housing. In some embodiments thearmature 171 can be longer or wider than the width and length of thecore housing 172. For example, a door opening can include a long lineararmature that is longer than a corresponding core housing. The armature171 or the armature 161 can also have a different general shape than thecore housing 172 or the core housing 162. For example, thecylindrically-shaped armature 161 can be paired with the U-shaped corehousing 172 for particular residual magnetic devices.

In the cylindrical configurations and the U-shaped configurations, thecontroller 164 or the controller 174 can sense that the moveable elementis generally near or in contact with the stationary element. Thecontroller 164 or the controller 174 can pulse a magnetization currentto the coil 163 or the coil 173 to latch the armature 161 to the corehousing 162 or the armature 171 to the core housing 172 in order to holdthe moveable element to the stationary element. With the residualmagnetic axial latch 160 or the residual magnetic axial latch 170latched the moveable elements generally cannot be moved with respect tothe stationary elements.

To release the latch, a remote access switch or release mechanism can beprovided. Once the switch or mechanism is activated, the controller 164or the controller 174 can provide a demagnetization current to the coil163 or the coil 173 in order to unlatch the armature 161 from the corehousing 162 or the armature 171 from the core housing 172. When theresidual magnetic axial latch 160 or the residual magnetic axial latch170 is unlatched, the moveable elements can again be moved with respectto the stationary elements.

In some embodiments, the armatures 161 and 171 can pivot away and towardthe core housings 162 and 172. As shown in FIG. 22, a residual magneticaxial latch 170 a can include an armature 171 a that can pivot on apivot point 179 a away from and toward a core housing 172 a. FIG. 22illustrates the armature 171 a engaged with the core housing 172 a.

FIG. 23 illustrates the armature 171 a disengaged from the core housing172 a and pivoted away from the core housing 172 a about the pivot point179 a. In some embodiments, a biasing member 180 a forces the armature171 a to pivot away from the core housing 172 a. The biasing member 180a can include one or more compression springs, tension springs,elastomeric members, wedges, and/or foams.

FIG. 24 illustrates a residual magnetic axial latch 170 b according toone embodiment of the invention. The residual magnetic axial latch 170 bcan include an armature 171 b, a core housing 172 b, a coil 173 b, abiasing member 180 b, and a latch 181 b with a latch protrusion 182 b.FIG. 25 illustrates a side view of the residual magnetic axial latch 170b. As shown in FIG. 25, the latch 181 b can include an input mechanism183 b. A force can be applied to the input mechanism 183 b to rotate thelatch 181 b about a latch pivot point 184 b. In some embodiments, theinput mechanism 183 b can be coupled to a lid, a door handle, or anothermoveable element (not shown). A manual force can be applied to the inputmechanism 183 b by moving the lid, the door handle, or the moveableelement.

To unlatch the residual magnetic axial latch 170 b, the latch 181 b canbe rotated. In some embodiments, the rotational path of the latch 181 bmoves the latch protrusion 182 b down and through the middle of theU-shaped core housing 172 b. When the core housing 172 b is engaged withthe armature 171 b, however, the latch 181 b cannot be rotated since therotational path of the latch 181 b is inhibited by the position of thearmature 171 b. In some embodiments, with the armature 171 b engagedwith the core housing 172 b, the latch 181 b cannot be rotated in orderto clear the latch protrusion 182 b from the U-shaped core housing 172b.

To unlatch the residual magnetic axial latch 170 b, the armature 171 bcan be disengaged from the core housing 172 b and pivoted about a pivotpoint 179 b to allow the latch 181 b to rotate and swing the latchprotrusion 182 b out of contact with the core housing 171 b. In someembodiments, the biasing member 180 b can force the armature 171 b topivot out of contact with the core housing 172 b. The biasing member 180b can include one or more compression springs, tension springs,elastomeric members, wedges, and/or foams.

FIG. 26 illustrates the residual magnetic axial latch 170 b with thelatch 181 b unlatched from the core housing 172 b. In some embodiments,with the latch 181 b unlatched from the core housing 172 b, a door, lid,or other moveable element can be moved and an entry, compartment, orother stationary element can be accessed, such as a building, a glovecompartment, or a vehicle trunk.

FIG. 27 illustrates a residual magnetic axial latch 170 c according toanother embodiment of the invention. As shown in FIG. 27, the residualmagnetic axial latch 170 c can include an armature 171 c, a core housing172 c, and a coil 173 c. In some embodiments, the armature 171 c canpivot on a pivot point 179 c. The residual magnetic axial latch 170 ccan also include a biasing member 180 c, a rotor latch 181 c with alatch protrusion 182 c that rotate on a pivot point 184 c, and a linkagesystem or mechanism 185 c. In some embodiments, the linkage mechanism185 c can include a toggle link that connects the armature 171 c and thecore housing 172 c with the rotor latch 181 c. The linkage mechanism 185c can transfer movement of the rotor latch 181 c to the armature 171 c.The linkage mechanism 185 c can pivot on a pivot point 186 c.

FIG. 27 illustrates the residual magnetic axial latch 170 c in anengaged state with the armature 171 c engaged with the core housing 172c with a residual magnetic force. In some embodiments, the rotor latch181 c includes a release portion 187 c that can accept a striker pin orbar 188 c. The striker bar 188 c can be coupled to a door, a lid,another moveable element, or a stationary element. In an engaged state,the rotor latch 181 c can be retained in a locked state that preventsthe striker bar 188 c from being released and a moveable element frombeing moved.

To release the striker bar 188 c from the release portion 187 c, therotor latch 181 c can be rotated. When the rotor latch 181 c rotates,the latch protrusion 182 c can force the linkage mechanism 185 c torotate or pivot. When the linkage mechanism 185 c rotates or moves, thelinkage mechanism 185 c can force the armature 171 c to move. When thearmature 171 c is engaged with the core housing 172 c, the armature 171c cannot move. Therefore, the linkage mechanism 185 c and the rotorlatch 181 c also cannot rotate or pivot.

As shown in FIG. 28, the armature 171 c can be disengaged from the corehousing 172 c and the armature 171 c can pivot about the pivot point 179c. The armature 171 c can pivot and allow the linkage mechanism 185 cand the rotor latch 181 c to rotate. The striker bar 188 c can apply atension force to the rotor latch 181 c that, when the rotor latch 181 cis allowed to move, can force the rotor latch 181 c to rotate to an openposition. The open position of the rotor latch 181 c can release thestriker bar 188 c, and the moveable element coupled to the striker bar188 c can be moved.

In some embodiments, after the striker bar 188 c is released, theresidual magnetic axial latch 170 c can be reset. The armature 171 c canbe reengaged with the core housing 172 c by supplying a magnetizationcurrent to the coil 173 c. In some embodiments, the biasing member 180 ccan force the armature 171 c to pivot toward the core housing 172 c. Thebiasing member 180 c can include one or more compression springs,tension springs, elastomeric members, wedges, and/or foams.

FIG. 29 illustrates the residual magnetic axial latch 170 c reset. Withthe residual magnetic axial latch 170 c reset, the rotor latch 181 c canaccept the striker bar 188 c. When the rotor latch 181 c accepts thestriker bar 188 c, the force of the striker bar 188 c can rotate therotor latch 181 c back to a closed position, as shown in FIG. 27. Insome embodiments, the toggle link of the linkage mechanism 185 c canfreely swing open until the rotor latch 181 c rotates into the closedposition shown in FIG. 27. In some embodiments, the latch protrusion 182c can stop rotation of the rotor latch 181 c at an open position.

FIG. 30 illustrates a residual magnetic axial latch 170 d according toanother embodiment of the invention. As shown in FIG. 30, the residualmagnetic axial latch 170 d can include an armature 171 d, a core housing172 d, and a coil 173 d. In some embodiments, the armature 171 d canrotate on a pivot point 179 d. The residual magnetic axial latch 170 dcan also include a biasing member 180 d, a rotor latch 181 d with alatch protrusion 182 d that rotate on a pivot point 184 d, and a linkagemechanism 185 d. In some embodiments, the linkage mechanism 185 dincludes a pawl that links the armature 171 d and the core housing 172 dwith the rotor latch 181 d. The linkage mechanism 185 d can pivot on apivot point 186 d.

FIG. 30 illustrates the residual magnetic axial latch 170 d in anengaged state with the armature 171 d engaged with the core housing 172d with a residual magnetic force. In some embodiments, the rotor latch181 d includes a release portion 187 d that can accept a striker pin orbar 188 d. The striker bar 188 d can be coupled to a moveable element,such as a door handle, a lid, or a stationary element. In an engagedstate, the rotor latch 181 d can be retained in a locked state thatprevents the striker bar 188 d from being released and, therefore,prevents the moveable element from moving.

To release the striker bar 188 d from the release portion 187 d, therotor latch 181 d can be rotated. When the rotor latch 181 d rotates,the attempted rotation of the latch protrusion 182 d can force thelinkage mechanism 185 d to rotate or pivot. The linkage mechanism 185 dcan rotate about pivot point 186 d. As the linkage mechanism 185 drotates, the linkage mechanism 185 d can attempt to force the armature171 d to pivot about the pivot point 179 d and move away from the corehousing 172 d. When the armature 171 d is engaged with the core housing172 d, however, the armature 171 d cannot pivot and, therefore, thelinkage mechanism 185 d and the rotor latch 181 d also cannot rotate.

As shown in FIG. 31, the armature 171 d can be disengaged from the corehousing 172 d and can pivot about the pivot point 179 d. The armature171 d can pivot to allow the linkage mechanism 185 d and the rotor latch181 d to rotate. The rotor latch 181 d can be rotated to an openposition in order to release the striker bar 188 d.

In some embodiments, after the rotor latch 181 d is opened and thestriker bar 188 d is released, the residual magnetic axial latch 170 dcan be reset. The armature 171 d can be engaged with the core housing172 d by supplying a magnetization current to the coil 173 d. In someembodiments, the biasing member 180 d can force the linkage mechanism185 d to rotate to a reset position. The rotation of the linkagemechanism 185 d can force the armature 171 d to pivot toward the corehousing 172 d. The biasing member 180 d can include one or morecompression springs, tension springs, elastomeric members, wedges,and/or foams.

FIG. 32 illustrates the residual magnetic axial latch 170 d reset. Byresetting the residual magnetic axial latch 170 d, the rotor latch 181 dcan be in an open position such that the rotor latch 181 d can acceptthe striker bar 188 d. In some embodiments, the force of accepting thestriker bar 188 d can force the rotor latch 181 d to rotate back to aclosed position. The latch protrusion 182 d can stop rotation of therotor latch 181 d at a closed position.

FIG. 33 illustrates another residual magnetic axial latch 170 eaccording to one embodiment of the invention. As shown in FIG. 33, theresidual magnetic axial latch 170 e can include an armature 171 e, acore housing 172 e, and a coil 173 e. The residual magnetic axial latch170 e can also include a biasing member 180 e, a rotor latch 181 e witha latch protrusion 182 e that rotates on a pivot point 184 e, and alinkage mechanism 185 e. In some embodiments, the rotor latch 181 eincludes a release portion 187 e that can accept a striker pin or bar188 e. In an engaged state, the rotor latch 181 e can be retained in alocked state that prevents the striker bar 188 e from being released.

The linkage mechanism 185 e can connect the core housing 172 e with therotor latch 181 e. The linkage mechanism 185 e can include a pin slot191 e that accepts a pin 192 e. The pin 192 e can be coupled to thearmature 171 e. The pin slot 191 e can also include a pin biasing member193 e that forces the pin slot 191 e to remain in contact with the pin192 e. The pin biasing member 193 e can include one or more compressionsprings, tension springs, elastomeric members, wedges, and/or foams.

In some embodiments, the armature 171 e is mounted substantiallystationary and the coil 173 e is wrapped around the armature 171 e. Thecore housing 172 e can pivot away from and toward the armature 171 eabout a pivot point 189 e. In some embodiments, as the core housing 172e pivots, the linkage mechanism 185 e can slide or move about the pin192 e. The linkage mechanism 185 e can slide or move and engage or catchthe latch protrusion 182 e.

FIG. 33 illustrates the residual magnetic axial latch 170 e in anengaged state with the core housing 172 e engaged with the armature 171e with a residual magnetic force. To release the striker bar 188 e fromthe release portion 187 e, the rotor latch 181 e can be rotated. Whenthe rotor latch 181 e rotates, the latch protrusion 182 e forces thelinkage mechanism 185 e to rotate. When the core housing 172 e isengaged with the armature 171 e, however, the linkage mechanism 185 ecannot slide and/or rotate, and therefore, the rotor latch 181 e alsocannot rotate.

As shown in FIG. 34, with the core housing 172 e disengaged from thearmature 171 e, the core housing 172 e can pivot on the pivot point 189e in order to allow the linkage mechanism 185 e to move or slide aboutthe pin 192 e and to disengage the linkage mechanism 185 e from therotor latch 181 e. The rotor latch 181 e can then be rotated to an openposition in order to release the striker bar 188 e.

In some embodiments, after the rotor latch 181 e is opened and thestriker bar 188 e is released, the residual magnetic axial latch 170 ecan be reset. The core housing 172 e can be reengaged with the armature171 e by supplying a magnetization current to the coil 173 e. Thebiasing member 180 e can force the core housing 172 e to pivot about thepivot point 189 e toward the armature 171 e. The biasing member 180 ecan include one or more compression springs, tension springs,elastomeric members, wedges, and/or foams.

In some embodiments, a biasing member 190 e can force the linkagemechanism 185 e to slide or move back to a reset position as shown inFIG. 35. The basing member 190 e can include one or more compressionsprings, tension springs, elastomeric members, wedges, and/or foams.FIG. 35 illustrates the residual magnetic axial latch 170 e in a resetposition. By resetting the residual magnetic axial latch 170 e, therotor latch 181 e can accept the striker bar 188 e again and can rotateback to a closed position. The latch protrusion 182 e can stop rotationof the rotor latch 181 e at a closed position against the linkagemechanism 185 e.

As described and illustrated with respect to FIGS. 24-35, residualmagnetic axial latches can indirectly provide a latching force through alinkage mechanism or system. In some embodiments, residual magneticaxial latches can use residual magnetic forces to engage an armature anda core housing that are non-integrated parts of a latching mechanism,such as a rotor latch. Residual magnetic axial latches can also directlyprovide a latching force by integrating the residual magnetic componentswith the latching mechanism. In some embodiments, an integrated residualmagnetic axial latch can include a core housing that is coupled to astationary element and an armature that is coupled to a moveableelement. A residual magnetic latching mechanism, such as a rotor latch,can also be integrated with a core housing or an armature to provide anintegrated residual magnetic axial latch.

A residual magnetic axial latch can include an armature that movesaxially away from a core housing, that pivots away from a core housing,and/or that slides linearly past a core housing.

The residual magnetic devices described above can also provide aninfinitely-variable door check system in which a vehicle door can belocked and held at infinite positions while being opened or closed. Thecore housing and the armature can remain in a generally closerelationship while the vehicle door is opening or closing. In someembodiments, a controller can monitor the movement of the vehicle door.When the vehicle door is held generally stationary for a predeterminedamount of time or when no force is being applied to the vehicle door,the controller can generate a magnetization pulse in order to create aresidual magnetic force between the core housing and armature that locksthe door in its current position. The controller can also sense a forceor torque applied to the vehicle door. Upon sensing a force or torque,which can indicate that a user wants to open, close, or change theposition of the vehicle door, the controller can generate ademagnetization current to reduce or substantially eliminate theresidual magnetic force and unlock the position of the vehicle door.

The functionality of the infinitely-variable door check system can alsobe applied to vehicle seat movement along a seat track. A core housingcan be coupled to the seat track and an armature can be coupled to thevehicle seat that moves along the seat track. When a residual magneticforce is present between the core housing and the armature, the vehicleseat can be locked in a position along the seat track. In someembodiments, a controller can sense the lifting of a lever or thepressing of a button by a user and can generate a demagnetizationcurrent to reduce or substantially eliminate the residual magneticforce. The demagnetization current can unlock the vehicle seat to allowa user to move the vehicle seat along the seat track. With the seatunlocked, the user can select a position for the vehicle seat. The usercan also release a lever, press a button, or hold the vehicle seat inthe desired position for a predetermined amount of time causing thecontroller to transmit a magnetization current. The magnetizationcurrent can create a residual magnetic force between the core housingand the armature to lock the vehicle seat in its current position. Inaddition to a linear seat position adjustment system, seat positionadjustment systems can also be used to provide angularinfinitely-variable seat positioning. Furthermore, the functionalityprovided with the seat position adjustment system to adjust the linearand angular position of a seat can also be applied to headrestadjustments.

In another embodiment of the invention, the angular (“tilt”) positionand/or telescoping position of a steering wheel coupled to a vehicle canbe adjusted using an angular infinitely-variable adjustment system. Bycoupling a core housing to the instrument panel or another stationarycomponent and coupling an armature to the steering column assembly orthe steering wheel shaft, or vice versa, the angular and/or telescopingpositions of the steering wheel can be adjusted and then locked in aninfinite number of positions in order to provide a more customizedposition for a user.

Residual magnetic braking systems according to several embodiments ofthe invention can be used to draw toward and/or hold stationary a movingcomponent with respect to a stationary component. Residual magneticclutch systems can also be designed according to several embodiments ofthe invention. A clutching device can be considered a special type ofbrake. A braking device can include a grounded component and a moveablecomponent. When the braking device is activated, the grounded componentinteracts with the movable component and causes the moveable componentto become grounded. Similarly, a clutching device can include a movablecomponent and a stationary component. The stationary component isstationary in the sense that it does not naturally or independently moveas the movable component. In comparison to a braking device, thestationary component of a clutching device is not grounded. When theclutch is activated, the movable component interacts with the stationarycomponent and causes the stationary component to move as the moveableelement.

FIG. 36 illustrates a residual magnetic clutch system 194 according tosome embodiments of the invention. The clutch system 194 can include afirst element 195, a core housing 196, a second element 197, and anarmature 198. In some embodiments, the constructions, properties, andoperations of the armature 198, the core housing 196, and/or the coil(not shown) are similar to the armature 18, the core housing 20, and thecoil 22 described with respect to the steering column lock 12. Theclutch system 194 can also include a controller (not shown) as describedwith respect to the steering column lock 12.

The core housing 196 can be coupled to the first element 195 such thatthe first element 195 moves with the core housing 196. The armature 198can be coupled to the second element 197 such that the second element197 moves with the armature 198. The second element 197 can also bepositioned adjacent, or in relatively close proximity to the firstelement 195. In some embodiments, the second element 197 can movelinearly along reference line 199. The second element 197 can movelinearly, rotationally, angularly, axially, and/or any combinationthereof.

As shown in FIG. 36, without a residual magnetic force between the corehousing 196 and the armature 198, the second element 197 moves freelyand the first element 195 is stationary. The first element 195 can bemoving independently of the second element 197 rather than beinggenerally stationary. As shown in FIG. 37, when a residual magneticforce is generated between the core housing 196 and the armature 198 bysupplying a magnetization current to the coil (not shown), the armature198 can be drawn toward the core housing 196 and the first element 195can be brought into contact with the second element 197 such that thefirst element 195 moves with the second element 197. FIGS. 36A and 37Aillustrate one embodiment of a freewheeling steering column lock thatoperates according to the general principles shown and described withrespect to FIGS. 36 and 37. In one embodiment, the armature 198 a can becoupled to the steering column shaft 197 a, and the core housing 196 acan be coupled to the steering column 195 a and/or the vehicle. Inanother embodiment, the armature 198 a can be coupled to the steeringcolumn 195 a and/or the vehicle and the core housing 196 a can becoupled to the steering column shaft 197 a. When a residual magneticforce is present between the armature 198 a and the core housing 196 a,the steering column shaft 197 a rotates with the steering wheel (i.e.,the steering column is unlocked). When a residual magnetic force is notpresent between the armature 198 a and the core housing 196 a, thesteering column shaft 197 a and the steering wheel freewheels withrespect to the steering column 195 a and/or the vehicle (i.e., thesteering column is locked). The freewheeling steering column lock canalso include pins or other types of alignment components between thearmature 198 a and the core housing 196 a in order to properly align thesteering wheel with the steering column.

In some embodiments, the second element 197 can be coupled to a motorand the first element 195 can include a power take off accessory. Bygenerating a residual magnetic force between the core housing 196 andthe armature 198, the power take off accessory can be coupled to themotor such that the power take off accessory rotates with an outputshaft of the motor. In some embodiments, the first element 195 caninclude a power take off accessory that can be coupled to an airconditioning system. The air conditioning system (e.g., a compressorand/or a condenser) can operate when the power take off accessory iscoupled by the clutch system 194 to the output shaft of the motor. Whenthe residual magnetic force is not present, the power take off accessoryis no longer coupled to the output shaft of the motor and the airconditioning system no longer operates.

In other embodiments, the clutch system 194 can include one or morecomponents of door or compartment latches. The first element 195 caninclude a door handle and the second element 197 can include a doorlatch. When a residual magnetic force is not present between the corehousing 196 and the armature 198, the door handle and the door latch arenot coupled. Movement applied to the door handle is not transferred tothe door latch and the door cannot be opened. In some embodiments, thedoor handle and the door latch can be uncoupled when a door is locked.When a residual magnetic force is present between the armature 198 andthe core housing 196, the door handle can be coupled to the door latch.Movement of the door handle can then be transferred to the door latch.

The clutch system 194 can include one or more components of steeringcolumn locking system or device. The first element 195 can include asteering wheel and the second element 197 can include a steering shaft.When a residual magnetic force is not present between the core housing196 and the armature 198, the steering wheel and the steering shaft arenot coupled. In other embodiments, the steering column shaft can belocked to the steering column housing with a residual magnetic force andcan be spring-released to clutch the steering wheel in the correctorientation. Movement applied to the steering wheel is not transferredto the steering shaft. In some embodiments, the steering wheel and thesteering shaft can be uncoupled when a steering column is locked. When aresidual magnetic force is present between the armature 198 and the corehousing 196, the steering wheel can be coupled to the steering wheel.Movement of the steering wheel can then be transferred to the steeringshaft.

The roles of the first element 195 and second element 197 can beswitched. Without a residual magnetic force, the first element 195 canmove while the second element 197 is stationary.

Residual magnetic actuators or, in particular, variable reluctancerotary torque actuators with residual magnetic latches, can be designedaccording to several embodiments of the invention. A rotary torqueactuator can use a residual magnetic force to cause a first element tomove with respect to a second object. In some embodiments, the rotarytorque actuator can have a solenoid-type shape and the first element(i.e., the moveable object) can have a solenoid-type core that moveswithin the solenoid-shaped actuator. Variable reluctance rotary torqueactuators with residual magnetic latches can be used for a power latchrelease for vehicular keyless and passive entry systems including doorlatches, rear compartment or trunk latches, and hood latches. Rotarytorque actuators with residual magnetic latches can be used in shockabsorbers and other suspension tuning components. Rotary torqueactuators with residual magnetic latches can be used in a cinching doorlatch. A cinching door latch can include a biasing element, such as aspring, that is compressed when a door is opened. A rotary torqueactuator with a residual magnetic latch can release the spring to closethe door. Rotary torque actuators with residual magnetic latches can beused in steering column locking systems and devices. In someembodiments, a steering column locking system can include a cam or lockbolt that can be moved by a rotary torque actuator with residualmagnetic latch into a steering shaft so that a steering wheel cannot berotated. Rotary torque actuators with residual magnetic latches can beincluded in pilot control devices and can generate a majority of theirload or force from a primary load-bearing device, such as wrap springclutches, dog clutches, and multi-plate friction clutches or ball andramp clutches. Components of the rotary torque actuator with theresidual magnetic latch can be positioned between a load and a primaryload-bearing device to transfer the load of the primary load-bearingdevice.

FIG. 38 illustrates a variable reluctance rotary torque actuator with aresidual magnetic latch 200. In some embodiments, the rotary torqueactuator with the residual magnetic latch 200 can be used in a doorlatch systems and/or latch release systems. The rotary torque actuatorwith residual magnetic latch 200 can include an armature 202, a corehousing 204, a coil 206, two core stops 208, a biasing member 210 (e.g.,one or more compression springs, tension springs, elastomeric members,wedges, and/or foams), and a controller 212. In some embodiments, theconstructions, properties, and operations of the armature 202, the corehousing 204, the coil 206, and/or the controller 212 are similar to thearmature 18, the core housing 20, the coil 22, and the controller 24described with respect to the steering column lock 12. In someembodiments, the coil 206 and the core housing 204 can be U-shaped asshown and described above with respect to FIGS. 18-21 illustratingembodiments of residual magnetic axial latches.

As shown in FIG. 38, when a residual magnetic force is not present, thearmature 202 is not engaged with the core housing 204 and the armature202 does not contact the core stops 208. The biasing member 210 canprovide a biasing force that prevents the armature 202 from engagingwith the core housing 204 when a residual magnetic force is not present.The rotary torque actuator with residual magnetic latch 200 cansubstantially integrate two magnetic circuits: a rotary torque actuatorcircuit and a residual latching circuit. In some embodiments, the twomagnetic circuits can use the coil 206 to drive the armature 202 from anopen position, as shown in FIG. 38, to a closed residually-latchedposition, as shown in FIG. 40. The magnetic circuits can use differentmagnetic air gaps during operation of the rotary torque actuator. Forexample, the rotary torque actuator magnetic circuit can use a magneticair gap 208 a, and the residual magnetic latch circuit can use amagnetic air gap 208 b. The magnetic air gap 208 b can be formed whenthe armature 202 is in the closed position, as shown in FIG. 40. In someembodiments, the magnetic air gap 208 a remains constant through therotational travel of the armature 202, and the magnetic air gap 208 bvaries from being the largest in size at an open position of theactuator 202 to being the smallest in size at a closed position of thearmature 202 when the armature 202 is making contact with the core stops208. The magnetic air 208 a can be approximately 0.002 inches, and themagnetic air gap 208 b can be approximately 0.005 inches.

The size of the air gaps 208 a and 208 b can direct the magnetic fluxduring operation of the rotary torque actuator. For example, during therotary actuation operation of the rotary torque actuator, the air gap208 a is the smallest and the least resistant air gap. Therefore, asubstantial portion of the circuit's flux capacity flows through themagnetic air gap 208 a. Similarly, when the armature 202 is latched, asshown in FIG. 40, the air gap 208 b is the smallest air gap. Therefore asubstantial portion of the circuit's flux capacity shall flow throughthe air gap 208 b. The armature 202 of the rotary actuator changes thereluctance or permeance of the air gap 208 b as it moves, and amechanical force or torque is generated by the change in reluctance. Asthe armature 202 approaches the core stops 208, the armature 202 cancontinue to accelerate as the flux path changes from air gap 208 a toair gap 208 b, and as the air gap 208 b goes small the tractive loadsincrease the inverse square of the distance.

As shown in FIG. 39, when a magnetization current is applied to the coil206 by the controller 212, the coil 206 creates a magnetic field 230whose direction and path are indicated by the arrows. It should beunderstood that the direction of the field is dependent on the directionof the magnetization current applied to the coil 206. The magnetic field230 can also be generated to flow in the opposite direction as shown inFIG. 39. In some embodiments, the magnetic field 230 follows a path ofleast resistance (i.e., a path with minimal air gaps). The magneticfield 230 can travel through the material of the core housing 204 andarmature 202 with less resistance than it can travel through air. Inother words, the magnetic field 230 can switch between two substantiallyintegrated magnetic circuits as the magnetic air gap between thearmature 202 and the core housing 204 changes from a large and constantmagnetic air gap when the armature 202 is rotating or beginning torotate (as shown in FIG. 39) to a small magnetic air gap and asubstantially closed magnetic path between the armature 202 and the corehousing 204 when the armature 202 is no longer rotating (as shown inFIG. 40).

As the magnetic field 230 begins to draw the armature 202 closer to thecore stops 208 of the core housing 204, the armature 202 begins torotate about a pivot and decreases an air gap between the armature 202and the core stops 208. The armature 202 rotates due to the tangentialcomponent of the magnetic field 230 and the reluctance change of the airgap 208 a. The movement, speed, and torque of the armature 202 candepend on the magnitude of the magnetization current provided to thecoil 206, the permeance of the material used, and the rate at which airgap 208 b diminishes prior to making contact with the core stops. Whenthe armature 202 is held stationary by the core stops 208, the residualmagnetic force in the armature 202 increases in the form of torque untilthe material of the armature 202 and core housing 204 magneticallysaturates.

The rotation of the armature 202 can be limited by the core stops 208.When the armature 202 is held against the core stops 208, the circuitforms a magnetic closed path conducive to setting an irreversibleresidual field, and the armature 202 is latched, as shown in FIG. 40.After the armature 202 is latched, the controller 212 can stop applyingthe magnetization current to the coil 206. The armature 202 remainslatched to the core housing 204 at the core stops 208 by the residualmagnetic force. The magnetic field 230 can flow through the latch points(i.e., where the armature 202 meets the core stops 208), because thelatch points represent the smallest air gap, and thus, offer the leastresistance.

To unlatch the rotary torque actuator and the residual magnetic latch200, the residual magnetic force can be nullified by reversing themagnetization current supplied to the coil 206 by the controller 212.The demagnetization current reverses the direction of the magnetic field230 and balances the residual magnetic flux density of the material ofthe core housing 204 and armature 202. FIG. 41 illustrates thedemagnetization current being supplied to the coil 206 and a resultingmagnetic field 240. When the residual magnetic flux level is nullified,the armature 202 is again free to rotate back to the open position anddisengage from the core housing 204. The biasing member 210 biases thearmature 202 to the disengaged position shown in FIG. 38.

In some embodiments, the residual magnetic latching rotary actuator canbe used for vehicle or building access. A handle for a door can becoupled to the core housing 204, such that a force applied to the handlecan be transferred to the core housing 204. A force transferred to thecore housing 204 can be further transferred to the armature 202, whenthe armature 202 is engaged or latched to the core housing 204.

FIG. 42 illustrates a rotary torque actuator with a residual magneticlatch 300 to which a door handle force is applied, as indicated by arrow302. FIG. 42 illustrates the residual magnetic latch 300 of the rotarytorque actuator in a latched or door-unlocked state where the armature202 is engaged with the core housing 204. With the armature 202 latchedto the core housing 204, the door handle force 302 can cause the corehousing 204 and the armature 202 to rotate about a common pivot 303. Therotation of the armature 202 about the pivot 303 can cause the armature202 to engage a door latch pawl 304 in order to unlock or unlatch thedoor.

In contrast, FIG. 43 illustrates the rotary torque actuator with theresidual magnetic latch 300 in an unlatched or door-locked state wherethe armature 202 is disengaged from the core housing 204. The doorhandle force 302 is only transferred to the core housing 204, whichrotates on the pivot 303. However, the door handle force 302 is nottransferred to the armature 202. Without the rotation of the armature202, the door latch pawl 304 cannot be engaged to unlock or unlatch thedoor.

The rotary torque actuator with the residual magnetic latch 300 can beused in passive entry access systems. When the door handle is pulled, anauthorization is activated. If entry is authorized, the armature 202 canbe latched to the core housing 204 at the core stops 208, and thearmature 202 can contact the door pawl latch 304 in order to unlock oropen the door.

Rotary torque actuators with residual magnetic latches can be includedin latch devices and systems according to several embodiments of theinvention. FIG. 44 illustrates a front view of a gear-driven latchsystem 400. The gear-driven system 400 can include a clutch or pawl 402and a rotor latch 404. The pawl 402 can rotate about a pivot 406 and thelatch 404 can rotate about a pivot 408. In some embodiments, the pawl402 and the latch 404 can include one or more gear teeth 412 that caninterlock to transfer rotation from one gear to the other. The latch 404can also include an opening 416 that allows a pin or striker bar 418 tomove or be released from the latch 404. In some embodiments, the pin orstriker bar 418 can be coupled to a door (not shown) or another openingor unlatching mechanism, such as a trunk lid or a hood. Movement of thedoor handle can attempt to move the pin or striker bar 418 along thephantom path 419 and, consequently, rotate the latch 404. In someembodiments, releasing the pin or striker bar 418 can unlatch a door oranother locked or latched device, such as a rear compartment or hood, sothat the door, the rear compartment, or the hood can be opened.

When the gear-driven system 400 is in a locked position, as shown inFIG. 44, the pin or striker bar 418 cannot be moved along the phantompath 419 due to the position of the release portion 416. To release thepin or striker bar 418, the latch 404 can be rotated about the pivot 408until the release portion 416 is aligned with the phantom path 419. Asshown in FIG. 47, when the release portion 416 is aligned with thephantom path 419, the pin or striker bar 418 is free to move out ofengagement with the latch 404.

In some embodiments, a residual magnetic rotation blocking device 420,similar to the one described above for the vehicle ignition assembly 80,can regulate the rotation of the pawl 402 and the latch 404. FIG. 45illustrates a cross-sectional view of the gear-driven system 400 (takenalong reference line 45 illustrated in FIG. 44) including the rotationblocking device 420. The rotation blocking device 420 can include a corehousing 421, a coil 422, and an armature 424. In some embodiments, theconstructions, properties, and operations of the armature 424, the corehousing 421, and the coil 422 are similar to the armature 18, the corehousing 20, and the coil 22 described with respect to the steeringcolumn lock 12. The rotation blocking device 420 can also include acontroller as described with respect to the steering column lock 12. Therotation blocking device 420 can also include a lever or actuator 425.The lever 425 can provide a manual release mechanism 47. In otherembodiments, the manual release mechanism 47 can include a jack screw(as shown and described with respect to FIG. 5). In still otherembodiments, the manual release mechanism 47 can include a cam or awedge. The cam or wedge can be used with a cable-release configuration.

FIG. 45 illustrates the rotation blocking device 420 in a locked stated.The rotation blocking device 420 is locked by applying a magnetizationcurrent to the coil 422 to create a magnetic field that locks thearmature 424 to the core housing 421. Once the magnetic force is createdand the armature 424 is drawn to the core housing 421, the magnetizationcurrent applied to the coil 422 is no longer needed.

In some embodiments, the core housing 421 can be attached to a generallystationary object, such as a vehicle or door frame. When the rotationblocking device 420 is in a locked state, the armature 424 is locked orengaged with the core housing 421, and, thus, cannot move (i.e., rotate)relative to the core housing 421. In some embodiments, the armature 424and the pawl 402 can include one or more ratchet teeth 426 that cantransfer rotation between the pawl 402 and the armature 424 in onedirection. When the armature 424 is locked to the core housing 421 andrestricted from rotating relative to the core housing 421, the pawl 402is also restricted from rotating in one direction due to the ratchetteeth 426. Likewise, when the pawl 402 cannot move, the latch 404 alsocannot move. Therefore, with the rotation blocking device 420 in alocked position, attempted movement of the pin or striker bar 418 alongthe phantom path 419 is unsuccessful, because rotation of the latch 404and the pawl 402 cannot be transferred to the armature 424, which islocked or engaged with the core housing 421.

In some embodiments, the armature 424 and the core housing 421 can alsoinclude a detent 430 configuration with one or more female recesses 430a and one or more corresponding male protrusions 430 b. The detentconfiguration 430 can provide an additional locking force. Even if thearmature 424 rotationally slips with respect to the core housing 421, anadditional axial force is required to overcome the detent configuration430 and move the male protrusions 430 b out of engagement with thefemale recesses 430 a.

To unlock the gear-driven system 400, the residual magnetic forceholding the armature 424 to the core housing 421 is reversed or nulledby applying a demagnetization current to the coil 422. FIG. 46illustrates a cross-sectional view of the gear-driven system 400 (takenalong reference line 46 illustrated in FIG. 47) including the rotationblocking device 420 in an unlocked state. In an unlocked state, thearmature 424 is no longer locked or engaged with the core housing 421and can rotate relative to the core housing 421. With the armature 424free to rotate, the pawl 402 and the latch 404 can also rotate.Attempted movement of the pin or striker bar 418 causes the latch 404 torotate and align the release portion 416 of the latch 404 with thephantom path 419 of the pin or striker bar 418. The pin or striker par418 can then be released from the latch 404. In some embodiments, afterthe latch 404 is rotated to reach an open or unlatched position, theresidual magnetic field can be regenerated or reset to reengage thearmature 424 with the core housing 421. FIG. 47 illustrates a front viewof the gear-driven system 400 with the release portion 416 positioned torelease the pin or striker bar 418. In some embodiments, releasing thepin 418 unlatches a door.

In some embodiments, after the armature 424 and the core housing 421 areengaged, the rotational blocking device 420 is reset. When the latch 404is in an open position, the latch 404 can re-receive the pin or strikerbar 418. In some embodiments, the force of receiving the pin or strikerbar 418 can rotate the latch 404 and the pawl 402 via ratcheting withrespect to the armature 424 to a closed or latched position. The ratchetteeth 426 prevent the latch 404 and the pawl 402 from rotating back toan open position while the armature 424 is engaged with the core housing421. Generally, while the armature 424 is engaged with the core housing421, the ratchet teeth 426 can allow rotation of the latch 404 and thepawl 402 from an open position to the closed position and can preventrotation of the latch 404 and the pawl 402 from the closed position tothe open position.

In some embodiments, the pawl 402 can be coupled to a biasing member434. The biasing member 434 can include one or more compression springs,tension springs, elastomeric members, wedges, and/or foams. The biasingmember 434 can return the latch 404 to a predetermined position (e.g.,the locked position) after the pin or striker bar 418 is released fromthe latch 404. The force of the biasing member 434 can cause the pawl402 to rotate and place the latch 404 back in a locked position. In someembodiments, another biasing member 434 a can also be used to keep thepawl 402 in contact with the armature 424 such that rotational movementis not lost between the components.

The system 400 shown in FIGS. 44-47 can provide a non-integrated latchsystem. As described above with respect to residual magnetic axiallatches, a latch system can also directly provide a latching force byintegrating a latching mechanism with at least one of a core housing andan armature. On the other hand, non-integrated latch systems can includea linkage mechanism or system that transfers a latching or a retainingresidual magnetic force between an armature and a core housing to aseparate latching mechanism, such as a rotor latch.

FIG. 48 illustrates a residual magnetic rotation inhibitor in the formof a linkage system 440 that includes the pawl 402 and the latch 404interconnected with a linkage bar 450. The linkage bar 450 can beconnected to the pawl 402 and the latch 404 with one or more fasteners452. The fasteners 452 can include screws, bolts, rivets, etc. In oneembodiment, the pawl 402 can be integrated with the armature of theresidual magnetic device. The pawl 402 can be rotated or driven by aforce from a striker bar 418 that rotates the latch 404 and the linkagebar 450. The residual magnetic rotation inhibitor is shown in thedemagnetized or disengaged state in FIG. 48. When the door, lid, ormovable element is closed, the striker bar 418 can drive the latch 404,the linkage bar 450, and the pawl 402. As the striker bar 418 begins torotate the latch 404, a switch or sensor can indicate movement of thelatch 404 and can signal a controller to apply a magnetization currentto the coil in the core housing that shares the same pivot as thearmature 402. When the link 450 has driven the pawl 402 to the positionshown in FIG. 49, the armature's detents can drop into the recesses onthe core housing, and power to the coil will time out or the sensor willdetermine that the event is finished and turn off power to the coil.FIG. 49 illustrates the armature of the pawl 402 magnetically attachedto the core housing in an engaged state. A load line 457 of the link 450is generally through the pivot 406, which adds greatly to the mechanicaladvantage of the residual magnetic rotary inhibitor device. The detentson the armature of the pawl 402, the link 450, and the latch 404 can allbe loaded by a door seal load and a return spring. When the core housingand the armature are demagnetized, the striker bar 418 can be released.It should be understood that the linkage bar 450 can also be connectedto the pawl 402 and the latch 404 in a near-over-center condition inorder to increase the disengaged and engaged force of the latch 404.

FIG. 50 illustrates a front view of a latch system 460 according toanother embodiment of the invention. In some embodiments, the latchsystem 460 can be used to lock or latch a compartment, such as a trunkof a vehicle. The latch system 460 can include a mounting plate 462. Themounting plate 462 can be attached or mounted to a compartment frame ora vehicle frame with one or more fasteners 463. The fasteners 463 caninclude screws, bolts, rivets, etc. The mounting plate 462 can alsoinclude an opening 464 that accepts a pin or striker bar 465. In someembodiments, releasing the pin or striker bar 465 from the opening 464can unlatch or open a compartment.

The latch system 460 can include an armature 466 and a rotor latch 467.The armature 466 can rotate about a pivot 468 and the rotor latch 467can rotate about a pivot 470. In some embodiments, the armature 466 canbe coupled to the rotor latch 467 by a pawl or ratchet clutch 472. Thepawl 472 can be coupled to the armature 466 by a fastener 473, which caninclude a bolt, a screw, a rivet, etc. In some embodiments, the pawl 472can also be coupled to the rotor latch 467 by a fastener (not shown).The pawl 472 can also interact with the rotor latch 467 using a ratchetconfiguration 474. As shown in FIG. 50, the pawl 472 can include aprotrusion 474 a and can rotate the rotor latch 466 by engaging with acorresponding recess 474 b of the rotor latch 467. When the protrusion474 a engages with the recess 474 b, the rotation of the rotor latch 467can be transferred to the pawl 472.

The rotor latch 467 can also include an opening 475 that allows the pinor striker bar 465 to move or be released from the opening 464 of themounting plate 462. In some embodiments, the mounting plate 462 can becoupled to an opening or unlatching mechanism, such as a trunk lid. Whenthe trunk lid, is opened or pulled away from the trunk frame, themounting plate 462 can move with the trunk lid, and the pin or strikerbar 465 can be released from the opening 464 of the mounting plate 462.

When the latch system 460 is in a locked or latched position, as shownin FIG. 50, the pin or striker bar 465 cannot be released from theopening 464 of the mounting plate 462 due to the position of the opening475 of the rotor latch 467. To release the pin or striker bar 465, therotor latch 467 can be rotated about the pivot 470 until the opening 475is aligned with the opening 464 of the mounting plate 462. When the dooris closed and the residual magnetic force is released, the rotor latch467 can transfer rotation from the pawl 472 to the armature 466. Asshown in FIG. 51, when the opening 475 of the rotor latch 467 is alignedwith the opening 464 of the mounting plate 462, the pin or striker bar465 is released from the mounting plate 462. As in the linkage system440 shown in FIGS. 48-49, the rotational inhibitor of the latch system460 can be the ground and the reaction point for latch-driven loads(i.e., seal loads, return spring loads, etc.). When the door, lid, orother moveable element is locked, the load can generally pass throughthe pawl 472 close to the center of the armature 466. Also, the line offorce when the device is loaded by latch seal forces can generally passthrough the residual magnetic armature pivot 468, thereby increasing themechanical advantage of the residual magnetic rotational inhibitorallowing the latch system 460 to handle large latch loads withoutunintentional release.

In some embodiments, the latch system 460 can include a residualmagnetic rotation blocking device 476, similar to the one illustratedand described with respect to the gear-driven system 400 and the linkagesystem 440. FIG. 53 illustrates a cross-sectional view of a portion ofthe latch system 460 (taken along reference line 53 illustrated in FIG.50) including the rotation blocking device 476. The rotation blockingdevice 476 can include a core housing 477, a coil 478, and an armature466. In some embodiments, the constructions, properties, and operationsof the armature 466, the core housing 477, and the coil 478 are similarto the armature 18, the core housing 20, and the coil 22 described withrespect to the steering column lock 12. The rotation blocking device 476can also include a controller as described with respect to the steeringcolumn lock 12.

FIG. 53 illustrates the rotation blocking device 476 in a locked stated.The rotation blocking device 476 is locked by applying a magnetizationcurrent to the coil 478 to create a magnetic field that locks thearmature 466 to the core housing 477. Once the magnetic force is createdand the armature 466 is drawn to the core housing 477, the magnetizationcurrent applied to the coil 478 is no longer needed.

In some embodiments, the core housing 477 can be attached to themounting plate 462. When the rotation blocking device 476 is in a lockedstate, the armature 466 is engaged with the core housing 477, and, thus,cannot rotate relative to the core housing 477. When the armature 466 isengaged with the core housing 477, the pawl 472 coupled to the armature466 is restricted from rotating. Likewise, when the pawl 472 cannotmove, the rotor latch 467 also cannot move. With the rotation blockingdevice 476 in a locked position, attempted movement of a trunk orcompartment lid, to which the mounting plate 462 is attached, isunsuccessful, because rotation of the rotor latch 467 and the pawl 472cannot be transferred to the armature 466.

In some embodiments, the armature 466 and the core housing 477 caninclude a detent 480 configuration with one or more female recesses 480a and one or more corresponding male protrusions 480 b. The detentconfiguration 480 can provide an additional locking force. Even if thearmature 466 rotationally slips with respect to the core housing 477, anadditional axial force is required to overcome the detent configuration480 and move the male protrusions 480 b out of engagement with thefemale recesses 480 a.

To unlock the latch system 460, the residual magnetic force holding thearmature 466 to the core housing 477 is reversed or nulled by applying ademagnetization current to the coil 478. FIG. 54 illustrates across-sectional view of a portion of the latch system 460 (taken alongreference line 54 illustrated in FIG. 51) including the rotationblocking device 476 in an unlocked state. In an unlocked state, thearmature 466 is no longer engaged with the core housing 477 and canrotate relative to the core housing 477. With the armature 466 free torotate, the pawl 472 and the rotor latch 467 can also rotate. Attemptedmovement of the mounting plate 462 can apply pressure or force(generated by the contact of the pin or striker pin 465 with the opening475 of the rotor latch 467) to the rotor latch 467 causing the rotorlatch 467 to rotate. Rotating the rotor latch 467 can align the opening475 of the rotor latch 467 with the opening 464 of the mounting plate462. The pin or striker bar 465 can then be released from the opening464 and the trunk or compartment lid can be opened. FIG. 51 illustratesa front view of the latch system 460 with the opening 475 of the rotorlatch 467 positioned to release the pin or striker bar 465.

In some embodiments, the residual magnetic latch system 460 can beimmediately reset (i.e., the residual magnetic rotation blocking device476 can be returned to a locked state) after the rotor latch 467 reachesthe open or unlatched position. FIG. 52 illustrates the latch system 460in a reset state. In some embodiments, when the residual magnetic forceis substantially nulled and the rotor latch 467 is opened, a biasingmember 482 a coupled to the rotor latch 467 forces the rotor latch 467to rotate. As shown in FIGS. 51 and 52, the rotation of the rotor latch467 caused by the biasing member 482 a and/or the force of the strikerbar 465 can force the protrusion 474 a of the pawl 472 to disengage withthe rotor latch 467. The biasing member 482 a can include one or morecompression springs, tension springs, elastomeric members, wedges,and/or foams. Pin or pawl guide 484 b causes the pawl 472 to rotate asthe pawl 472 is moved by the rotor latch 467. Protrusion 474 a isdisengaged from recess 474 b.

As shown in FIGS. 50-52, the pawl 472 can be coupled to a biasing member482 b. The biasing member 482 b can include one or more compressionsprings, tension springs, elastomeric members, wedges, and/or foams. Thebiasing member 482 b can return the pawl 472 to a predetermined position(e.g., a reset position) after the protrusion 474 a is released from therecess 474 b. In some embodiments, the force of the biasing member 482 aon the rotor latch 467 is greater than the force of the biasing member482 b on the pawl 472, such that protrusion 474 a of the pawl 472disengages from the recess 474 b of the rotor latch 467 and the pawl 472and the armature 466 return to a reset position. The latch system 460can include one or more guides 484 a, 484 b, and 484 c. The pawl guides484 a and 484 b can direct the position of the pawl 472, can restrictmovement of the pawl 472, and can guide the pawl 472 into a resetposition. Similarly, the rotor guide 484 c can direct and limit therotation of the rotor latch 467. The armature 466 can include a stopprotrusion 486. The stop protrusion 486 can interact or connect with anarmature stop 488. When the armature 466 rotates, the armature stop 488can connect with the stop protrusion 486 and block further rotation ofthe armature 466. In some embodiments, when the biasing member 482 areturns the pawl 472 to a reset position, the armature stop 488 canrestrict the armature 466 from rotating past or beyond a lockedposition.

As shown in FIG. 52, in a reset position, the latch system 460 can beready to receive the striker bar 465 again. In some embodiments, withthe pawl 472 and the armature 466 in a reset position, the rotationblocking device 476 is locked by applying a magnetization current to thecoil 478 to create a magnetic field that locks the armature 466 to thecore housing 477. Receiving the striker bar 465 can force the rotorlatch 467 to rotate and re-engage with the pawl 472, which is heldstationary by the residual magnetic force locking the armature 466 tothe core housing. Once the rotor latch 467 is re-engaged with the pawl472, the rotor latch 467 can be prohibited from rotating back to an openposition and the latch system 460 can be locked or latched as describedand illustrated above with respect to FIG. 50.

FIGS. 55 and 56 illustrate another residual magnetic latch system 490according to one embodiment of the invention. FIG. 55 illustrates afront view of the system 490, and FIG. 56 illustrates a cross-sectionalview of the system 490 taken across reference line 56 illustrated inFIG. 55. In some embodiments, the latch system 490 is used to lock andunlock a rear door or window hatch of a vehicle. The latch system 490can also be used in other applications to lock and unlock a moveableelement, such as a door, lid, hood, etc.

As shown in FIGS. 55 and 56, the system 490 can include a rotor latch491, a core housing 492, an armature 493, a coil 494, and a pawl 495.The system 490 can also include a controller 496. In some embodiments,the constructions, properties, and operations of the armature 493, thecore housing 492, the coil 494, and the controller 496 are similar tothe armature 18, the core housing 20, the coil 22, and the controller 24described with respect to the steering column lock 12.

As shown in FIG. 56, the rotor latch 491 and core housing 492 can be anintegrated component. The integrated rotor latch 491 and core housing492 and the armature 493 can rotate about a rotor shaft 497. Thearmature 493 can include one or more pawl stops 498, which can beengaged by the pawl 495. The pawl 495 can also rotate about a pawl shaft499.

FIGS. 55 and 56 illustrate the latch system 490 in an open position. Inan open position, the rotor latch 491 can receive a pin or striker bar500 into a release portion 491 a of the rotor latch 491. In someembodiments, the striker bar 500 can be attached to a moveable element,such as a rear hatch of a vehicle, and the latch system 490 can beattached to a stationary element, such as a trunk or vehicle frame. Inan open position, the armature 493 can engage with the core housing 492.As described above, the controller 496 can supply a magnetizing currentto the coil 494 until the core housing 492 is engaged with the armature493.

In some embodiments, when the armature 493 is engaged with the corehousing 492 and the moveable element (e.g., the hatch) is closed andmoved toward the stationary element, the striker bar 500 is received bythe release portion 491 a of the rotor latch 491. The force of thestriker bar 500 on the rotor latch 491 can rotate the rotor latch 491and the armature 493 in a counter clockwise direction (as shown in FIG.55). The rotor latch 491 and the armature 493 can rotate until the pawl495 engages one of the pawl protrusions 498 of the armature 493. Theforce of the pawl 495 against the pawl protrusion 498 can keep thearmature 493 and the rotor latch 491 that is integrated with the corehousing 492 from rotating clockwise and releasing the striker bar 500.With the rotor latch 491 in a latched position, the striker bar 500cannot be released from the release portion 491 a of the rotor latch491.

To release the striker bar 500 from the release portion 491 a, thecontroller 496 can demagnetize the armature 493 and the core housing492. Once the core housing 492 can rotate independently from thearmature 493, the rotor latch 491 and core housing 492 can rotate backto the initial open position releasing the striker bar 500. In someembodiments, the system 490 can include a biasing member 501 that canforce the rotor 491 back to an open position. The biasing member 501 caninclude one or more compression springs, tension springs, elastomericmembers, wedges, and/or foams. The system 490 can include a rotor guide502 that can prevent the rotor 491 from rotating past the open position.

Once the rotor 491 rotates back to the open position, the controller 496can set the residual magnetic load. Once the residual magnetic load isset, the core housing 492 can engage the armature 493 and the rotor 491can receive the striker bar 500 into the release portion 491 a again.

In some embodiments, the system 490 can include a detent configuration503. The detent configuration 503 can include one or more maleprotrusions 503 a on armature 493 or the rotor latch 491 that areassociated with each pawl stop 498. The core housing 492 can includecorresponding female recesses 503 b that interconnect with the maleprotrusions 503 a. The detent configuration 503 can ensure that when therotor latch 491 is released and rotated back to an open position, therotor latch 491 lines up with the armature 493 so that the next pawlstop 498 of the armature 493 will be caught by the next rotation of thearmature 493 by a predetermined angle. The number of protrusions 503 apositioned on the armature 493 or the rotor latch 491 can be determinedby the angular displacement or rotation of the rotor latch 491 from anopen position to a latched position. As shown in FIG. 55, the pawl stops498 can be positioned every 90° on the armature 493, such that the rotorlatch 491 rotates 90° to move from an open position to a closedposition. If, for example, the rotor displacement or rotation were 60°,the armature 493 could include six pawl stops 498 positioned every 60°.

The pawl 495 included in the system 490 can include other clutchsystems. For example, a strut configuration, a sprag configuration, aroller ramp configuration, etc., can be used in addition to or in placeof the pawl 495 and pawl stop 498 configuration as illustrated anddescribed above.

Residual pilot control devices can be designed according to severalembodiments of the invention. In some embodiments, residual magneticpilot control devices can generate a majority of their load or forcefrom a primary load-bearing device, such as wrap spring clutches, dogclutches, and multi-plate friction clutches or ball and ramp clutches.Residual magnetic pilot control devices can control the state of theprimary load-bearing device (i.e., on, off, or modulate), while notcontributing significantly to the overall load-bearing capacity of thesystem. Residual magnetic pilot control devices can be used inapplications that require relatively low weight and relatively smallsize with high latch and locking loads, such as door check systems, seatand steering wheel adjustment systems, etc. Residual magnetic pilotcontrol devices can also be used to load steering column locks, rearcompartment or trunk latches, door latches, and hood latches.Furthermore, residual magnetic pilot control devices can also be used invehicle brakes, vehicle clutches, or industrial clutches.

FIG. 57 illustrates one embodiment of a residual magnetic device as aresidual magnetic pilot control device 520 coupled to a wrap springdevice 530. The wrap spring device 530 can include a shaft 532, anarmature 534, a core housing 536, a coil 538, and one or more wrapsprings 540. In some embodiments, the constructions, properties, andoperations of the armature 534, the core housing 536, and the coil 538are similar to the armature 18, the core housing 20, and the coil 22described with respect to steering column lock 12. The pilot controldevice 520 can also include a controller similar to the controller 24described with respect to the steering column lock 12.

The wrap spring 540 can be used to brake or clutch the shaft 532. Insome embodiments, the wrap spring device 530 can control the tightnessof the multi-turn wrap spring 540 around the shaft 532. The tighter thewrap spring 540 around the shaft 532, the higher the brake/clutch torquecapacity. The number of turns of the wrap spring 540 can also influencethe torque capacity of the wrap spring device 530.

FIG. 58 illustrates a top or front view of the wrap spring device 530.The shaft 532 can pass through a sun gear 550 such that the rotation ofthe shaft 532 can be transferred to the sun gear 550. The shaft 532 canalso include gear teeth or grooves in addition to or instead of the sungear 550. The sun gear 550 can connect with one or more planetary gears554 and can cause the planetary gears 554 to rotate between the sun gear550 and an inner edge 558 of the armature 534. The inner edge 558 of thearmature 534 can include gear teeth that engage the planetary gears 554.

FIG. 59 is a cross-sectional view of the wrap spring device 530 (takenalong reference line 59 illustrated in FIG. 58) according to oneembodiment of the invention. The wrap spring device 530 shown in FIG. 59includes the sun gear 550, the planetary gears 554, one or more springcarriers 556, and the wrap springs 540. As shown in FIG. 59, eachplanetary gear 554 can include a pinion 560 that can engage one of thespring carriers 556 to transfer the rotation of the planetary gear 554to the spring carrier 556. Each wrap spring 540 can include a tighteningend 570 and a grounding end 580. The grounding end 580 of the wrapspring 540 can be attached to a stationary or grounded component, suchas the core housing 536 or a vehicle chassis (not shown). The tighteningend 570 can be attached to one of the spring carriers 556. When thetightening end 570 is rotated by rotating the spring carrier 556, thewrap spring 540 can tighten around the shaft 532. The opposite end ofthe spring 540 (i.e., the grounding end 580) is affixed to a stationaryreference position that keeps the entire spring 540 from rotating withthe shaft 532, rather than tightening around the shaft 532. In someembodiments the spring device 530 can include two wrap springs 540. Onespring 540 can tighten when the shaft 532 rotates in one direction, andthe other spring 540 can tighten when the shaft 532 rotates in theopposite direction.

When a residual magnetic force is created, the armature 534 can be drawntoward the core housing 536. The rotation of the shaft 532 istransferred through the sun gear 550 to the planetary gears 556. Theplanetary gears 554 rotate between the sun gear 550 and the inner edge558 of the armature 534. The rotation of the planetary gears 554 istransferred to the spring carriers 556 through the pinions 560 and tothe tightening ends 570 of the wrap springs 540. The rotating planetarygears 554 and the spring carriers 556 tighten the wrap springs 540around the shaft 532. The planetary gears 554 can regulate the rate ofthe tightening of the wrap springs 540. The rotation of the shaft 532can be faster or slower than the rotation of the planetary gears 554,such that the rotation of the shaft 532 may not be directly transferredto the wrap springs 540. The size of the planetary gears 554 can beadjusted to vary the tightening rate for of the wrap springs 540.

The winding of the wrap springs 540 around the shaft 532 can increasethe torque capacity of the wrap spring device 530 as an external torquethrough the shaft 532 is increased. A maximum torque capacity of thewrap spring device 530 can be determined by the friction coefficient ofthe wrap springs 540 against the shaft 532, the number of turns of thewrap springs 540, and/or the external torque exerted on the wrap springs540.

The residual magnetic pilot device 520 can also be used to release thetightened wrap springs 540 of the wrap spring device 530. When aresidual magnetic force is not present between the armature 534 and thecore housing 536, no rotational motion is transferred to the springcarriers 556. The pinions 560 are allowed to rotated 360 degrees aroundthe sun gear 550. The spring carriers 556 rotate freely, releasing thetension of the wrap springs 540. The wrap springs 540 can include aclearance fit so that the shaft 532 can rotate freely when the residualmagnetic force is not present. For example, the outer diameter of theshaft 532 can be smaller than the inner diameter of the wrap springs540.

In some embodiments, the pinions 560 of the planetary gears 554 maintaincontact with the spring carriers 556 when a residual magnetic force isnot present between the armature 534 and the core housing 536. Thelatching and unlatching of the armature 534 to the core housing 536 bythe creation and elimination of a residual magnetic force can beperformed to change the tightening rate of the wrap springs 540. Whenthe armature 534 is unlatched from the core housing 536 (i.e., when noresidual magnetic force is present between the armature 534 and the corehousing 536), the rotation of the shaft 532 can be transferred throughthe sun gear 550 to the planetary gears 554 and from the planetary gears554 to the armature 534. The rotation can cause the shaft 532, the sungear 550, the planetary gears 554, and the armature 534 to rotatetogether at the same rate. When the armature 534 is latched to the corehousing 536 (i.e., when a residual magnetic force is present between thearmature 534 and the core housing 536), the armature 534 can bestationary and the planetary gears 554 can rotate independently betweenthe sun gear 550 and the inner edge 558 of the armature 534. The size ofthe planetary gears 554 can cause the planetary gears 554 toindependently rotate at a different rate than the shaft 532. Thisindependent rotation can tighten the wrap springs 540 at a differentrate than the rotation of the shaft 532.

FIG. 60 illustrates a residual magnetic pilot control device 600 coupledto a cam clutch/brake device 602 according to another embodiment of theinvention. The cam clutch/brake device 602 can use a rotary input toclamp a dog clutch or a multi-plate friction pack. The higher the rotaryinput force into the cam clutch/brake device 602, the higher the clampload. The operation of the cam clutch/brake device 602 can be consideredparasitic, because it uses external energy to drive a clamp load.Examples of a parasitic operation can include a valve train of aninternal combustion engine and a human driver for a steering columnlock. The residual magnetic pilot control device 600 can act as anactuator such that it can connect an external power source to the camclutch/brake device 600 in order to turn on (connect) and turn off(disconnect) a power source to the cam clutch/brake device 600.

The cam clutch/brake device 602 and the residual magnetic pilot controldevice 600, shown in FIG. 60, can include a shaft 610, a drive sleeve612, an armature 614, a core housing 616, a coil 618, a ball and rampactuator 620, a clutch/brake device 624, and an external device 626. Insome embodiments, the constructions, properties, and operations of thearmature 614, the core housing 616, the coil, and/or the controller (notshown) are similar to the armature 18, the core housing 20, the coil 22,and the controller 24 described with respect to the steering column lock12.

In some embodiments, the states of the shaft 610 (i.e., whether theshaft is stationary or rotating) and the external device 626 can besynchronized when the clutch/brake device 624 is engaged. The externaldevice 626 can include a rotor latch and a striker rod or pin, agear-driven system, a power take-off accessory, a braking system withbrake pads, etc. The clutch/brake device 624 can include a dog clutch, amulti-plate friction clutch pack, or other suitable braking or clutchingdevices.

The ball and ramp actuator 620 can include a top ramp ring 630 coupledto the drive sleeve 612, a bottom ramp ring 635, and a rolling member orball 640 located between the top ramp ring 630 and the bottom ramp ring635. The opposed faces of the top ramp ring 630 and the bottom ramp ring635 can include variable depth grooves in which the ball 640 can travel.The grooves can be constructed such that rotation of one of the ramprings 630 and 635 can cause the ball 640 to travel along the grooves ofthe rings 630 and 635 in order to increase or decrease the distancebetween the ramp rings 630 and 635.

In one embodiment, the shaft 610 can rotate about an axis 650 in adirection indicated by arrow 652. The bottom ramp ring 635 can beattached to the shaft 610 such that the bottom ramp ring 635 can rotatewith the shaft 610. The top ramp ring 630 can be coupled to the drivesleeve 612, which can be coupled to the armature 614. The top ramp ring630 and drive sleeve 612 can move axially with the armature 614. The topramp ring 630 generally does not rotate with the shaft 610. The armature614 can be connected to the core housing 616 by one or more biasingmembers 660, such as one or more compression springs, tension springs,elastomeric members, wedges, and/or foams, which can allow the armature614 to move axially with respect to the core housing 616. In someembodiments, the core housing 616 can be stationary with respect to theshaft 610 and the armature 614.

As described above, a controller (not shown) can control the state ofthe residual magnetic pilot control device 600 by applying a current tothe coil 618 to create or nullify the residual magnetic force. When aresidual magnetic force is not present between the armature 614 and thecore housing 616, the armature 614 and the drive sleeve 612 can moveaxially substantially freely. As the shaft 610 rotates, the bottom rampring 635 can also rotate. The bottom ramp ring 635 can cause the ball640 to travel along the variable depth grooves of the top ramp ring 630and the bottom ramp ring 635. As the ball 640 travels, variations ingroove depth increase and decrease the distance between the top rampring 630 and the bottom ramp ring 635. The variations in groove depthcan be compensated by axial movement of the drive sleeve 612 allowed bythe biasing member 660. In some embodiments, the axial movement of thedrive sleeve 612 allows the bottom ramp ring 635 to maintain a generallystationary axial position on the shaft 610.

When a residual magnetic force is present between the armature 614 andthe core housing 616, the armature 614 can be locked to the core housing616 and the drive sleeve 612 and cannot move axially. As the shaft 610and the bottom ramp ring 635 rotate the ball 640 travels along thevariable depth grooves of the top ramp ring 630 and bottom ramp ring635. The drive sleeve 612 can be held axially stationary such that itcannot compensate for the variable depth grooves. As a result, thevariable depth grooves between the top ramp ring 630 and the bottom rampring 635 are compensated by axial movement of the bottom ramp ring 635allowed by a biasing support member 670. The biasing support member 670can allow the bottom ramp ring 635 to change its axial position withrespect to the shaft 610, and consequently, engage or load theclutch/brake device 624. In some embodiments, one part of theclutch/brake device 624 can be coupled to the bottom ramp ring 635. Whenone part of the bottom ramp ring 635 changes axial positions, that partof the clutch/brake device 624 can be brought into contact with anotherpart of the clutch/brake device 624.

In some embodiments, the clutch/brake device 624 can include a clutchthat transfers the state of the shaft 610 to the external device 626.The clutch/brake device 624 can also include a brake that transfers thestate of the external device 626 (i.e., a stationary state) to the shaft610. It should also be understood that the shaft 610 can be initiallystationary. Engaging the clutch/brake device 624 can initiate rotationof the shaft 610 in addition to or rather than stopping or transferringrotation.

FIG. 61 includes a vehicle 700 that can include one or more embodimentsof the residual magnetic devices of FIGS. 1-60. For example, the vehicle700 can include a residual magnetic steering column lock 712, a residualmagnetic ignition rotational inhibitor 714, one or more residualmagnetic rear compartment latches 716 (e.g., a power lock/unlock latch,a power release latch), a residual magnetic fuel filler door latchand/or cap lock 718, one or more types of residual magnetic seatmechanisms 720 (e.g., seat position adjuster, seat angle recliner,headrest adjuster), one or more residual magnetic side door latchlocking elements 722 (e.g., a power lock/unlock latch, a power releaseE-latch, a passive entry latch with dual inputs), a residual magneticdoor check 724 (e.g., a step less door check and/or a programmable endstop), one or more residual magnetic hood latch releases 726 (e.g., apower release latch, an active hood system release), one or moreresidual magnetic storage compartment latches 728 (e.g., a glove boxcompartment latch, a console latch, a pop glass latch), one or moreresidual magnetic devices for vehicle pedals 730 (e.g., parking brakepedal lock or accelerator pedal lock), residual magnetic window lifts732, residual magnetic seat belt retractor lock devices 734, residualmagnetic programmable window devices 736 (e.g., upper position locks,programmable end stops), a residual magnetic fan and/or air conditioningclutch devices 738, a residual magnetic transmission device 740 (e.g.,transmission shift interlock, BTSI lock, automatic transmission clutchactuator), residual magnetic suspension devices 742 (e.g., solelyresidual magnetic devices or a hybrid of hydraulic fluid and residualmagnetic devices for shock absorber valves or sway bar locks), residualmagnetic spare tire lifts 746 (e.g., cable locks), residual magneticretractable roof systems 748 (e.g., open/closed position latches), aresidual magnetic brake pad lock for a parking brake function 750, etc.Residual magnetic devices can be used in storage compartments incommercial vehicles (e.g., power release latches). Residual magneticdevices can be used in recreational vehicles (motorcycles, all terrainvehicles, snowmobiles, etc.) in steering column/handlebar locks orparking brake locks. Residual magnetic devices can be used in lawn andgarden vehicles in power take off clutch devices or parking brake locks.Residual magnetic devices can be used in tractor trailers in emergencybrake devices.

FIG. 62 includes a commercial or residential building 800 with a door802, a door frame 804, and a residual magnetic door lock 806. Theresidual magnetic door lock 806 can include an armature 808 coupled tothe door 802 and a core housing 810 coupled to the door frame 804, orvice versa. Residual magnetic window lock devices 812 can also be usedto lock windows 814 in the building 800. The doors 802 and/or thewindows 814 can be interior or exterior doors and/or windows. Residualmagnetic devices can be used on interior or exterior doors 802 inhotels, apartment buildings, condominiums, etc. Residual magneticdevices can be used on security gates around or vaults in residential orcommercial buildings.

Residual magnetic devices can be used in industrial components, such asindustrial ball or roller bearings (e.g., locking bearings), industrialfasteners (e.g., power engage/disengage fasteners), industrial clutches(e.g., conveyors, machinery, etc.), and industrial brakes (e.g.,material handling, machinery, etc.).

Embodiments of the invention can use residual magnetic technology toprovide shear brakes and shear clutches. Shear brakes and shear clutchescan allow the core housing and the armature to move or slide along aplane of contact. In addition, shear brakes and shear clutches can allowthe core housing and the armature to move (i.e., rotate, translate, or acombination thereof) independently of one another when a residualmagnetic force is not present and can force the core housing and thearmature to move dependently as a shear clutch or to not movedependently as a shear brake when the residual magnetic force ispresent.

Embodiments of the invention can also use residual magnetic technologyto provide detent brakes and detent clutches. Detent brakes and detentclutches can include one or more detents or blocking mechanisms thatseparate the core housing from the armature by a fixed distance. Whenthe core housing and the armature are separated by a fixed distance, thecore housing and the armature are allowed to move (e.g., rotate,translate, or a combination thereof) independently. Likewise, when thecore housing and the armature are not separated by a fixed distance(e.g., protrusions are aligned with recesses) they move dependently as adetent clutch or do not move dependently as a detent brake. The detentsor blocking mechanisms force the core housing and the armature to moveaxially away from one another before they can move independently of oneanother. For example, the rotational blocking device 78 illustrated anddescribed with respect to FIGS. 8 and 9, includes detents that positionand hold the core housing in relation to the armature. To release thecore housing from the armature in order to allow the core housing andthe armature to move independently, an axial force is required todisengage the detents. In some embodiments, a shear force is alsocreated as the protrusions and recesses move or slide along a plane ofcontact to disengage. Furthermore, a shear force can also be createdonce the detents are disengaged since the disengaged protrusionscontinue to create a plane of contact between the core housing and thearmature as the armature and/or the core housing rotates. Embodiments ofthe invention can also provide infinitely separated brakes and clutcheswhere the core housing and the armature move without substantiallycontacting.

Various additional features and advantages of the invention are setforth in the following claims.

The invention claimed is:
 1. A method of coupling and uncoupling a firstelement with respect to a second element, the method comprising:applying a magnetization current to form a substantially closed magneticpath between an armature and a core housing defining a magnetic air gapin order to create an irreversible residual magnetic force with amagnetic air gap energy of at least 6652 (line-amp-turn)/cm3; couplingthe first element to the second element due to the irreversible residualmagnetic force; applying a demagnetization current to null at least aportion of the irreversible residual magnetic force, wherein thedemagnetization current is sufficient to uncouple the first element fromthe second element; and uncoupling the first element from the secondelement in response to the nulling of at least a portion of theirreversible residual magnetic force through application of thedemagnetization current.
 2. The method of claim 1 and further comprisingcreating the irreversible residual magnetic force between the armatureand the core housing by providing a magnetization current to a coil. 3.The method of claim 2 and further comprising misaligning magneticdomains in at least one of the armature and the core housing in order tonull at least a portion of the irreversible residual magnetic force. 4.The method of claim 3 and further comprising restoring the irreversibleresidual magnetic force by providing the magnetization current again tothe coil.
 5. The method of claim 1 and further comprising creating theirreversible residual magnetic force in order to substantially prevent ashear force from causing movement between the armature and the corehousing.
 6. The method of claim 1 and further comprising creating theirreversible residual magnetic force in order to substantially prevent aforce from overcoming at least one detent between the armature and thecore housing.
 7. The method of claim 1 and further comprising creatingthe irreversible residual magnetic force in order to allow rotationalmovement of the first element.
 8. The method of claim 1 and furthercomprising creating the irreversible residual magnetic force in order toallow translational movement of the first element.
 9. The method ofclaim 1 wherein forming the substantially closed magnetic path includesforming the substantially closed magnetic path between the armature andthe core housing in order to create the irreversible residual magneticforce with a magnetic air gap of less than approximately 0.005 inchesbetween the core housing and the armature when the irreversible residualmagnetic force is present.
 10. The method of claim 1 and furthercomprising providing a core housing with a first cross-sectional area ofan inner core being substantially equal to a second cross-sectional areaof an outer core of the core housing, which is substantially equal to athird cross-sectional are of the armature, which is substantially equalto a fourth cross-sectional area of a yoke of the core housing.
 11. Themethod of claim 1 and further comprising constructing at least one ofthe armature and the core housing of at least one of SAE 1002 steel, SAE1018 steel, SAE 1044 steel, SAE 1060 steel, SAE 1075 steel, and SAE52100 steel.
 12. The method of claim 1 and further comprisingconstructing at least one of the armature and the core housing ofchromium steel.
 13. The method of claim 1 and further comprisingdetermining whether the irreversible residual magnetic force is presentbetween the core housing and the armature.
 14. The method of claim 1 andfurther comprising magnetically saturating substantially all portions ofthe core housing and the armature at substantially the same time. 15.The method of claim 1 wherein applying the demagnetization current tothe coil includes applying the demagnetization current to substantiallynull irreversible residual magnetic force between the core housing andthe armature.
 16. The method of claim 15 wherein applying thedemagnetization current to the coil includes providing a demagnetizationcurrent with a substantially constant value due to the core housing andthe armature being magnetically saturated when the irreversible residualmagnetic force is created.
 17. The method of claim 1 and furthercomprising providing a second element including a motor and a firstelement including a power take off accessory.
 18. The method of claim 17and further comprising providing a first element including a power takeoff accessory coupled to an air conditioning system.
 19. The method ofclaim 1 and further comprising providing a first element including adoor handle and a second element including a door latch.
 20. The methodof claim 1 and further comprising providing a first element including asteering wheel and a second element including a steering shaft.
 21. Themethod of claim 1 and further comprising providing at least one of afirst element and a second element that includes a portion of a tunablesuspension system.
 22. A method of coupling and uncoupling a firstelement with respect to a second element, the method comprising:providing a first level of power to a coil in order to create a firstirreversible residual magnetic force between a core housing and anarmature defining a magnetic air gap, the irreversible residual magneticforce having a magnetic air gap energy of at least 6652(line-amp-turn)/cm3, the first level of power not saturating the corehousing and the armature; coupling the first element to the secondelement due to the first irreversible residual magnetic force; applyinga demagnetization current to the coil sufficient to null theirreversible residual magnetic force and to uncouple the first elementand the second element; and uncoupling the first element and the secondelement in response to applying the demagnetization current.
 23. Themethod of claim 22 and further comprising providing a second level ofpower that is higher or lower than the first level of power to the coilin order to create a second irreversible residual magnetic force. 24.The method of claim 22 and further comprising modulating between atleast two levels of power in order to create at least two irreversibleresidual magnetic forces.
 25. The method of claim 22 and furthercomprising providing a constant level of power to the coil in order tocreate a constant irreversible residual magnetic force that is less thana material saturation residual magnetic force.
 26. A method of couplingand uncoupling a first element with respect to a second element, themethod comprising: applying a magnetization current to form asubstantially closed magnetic path between an armature and a corehousing defining a magnetic air gap in order to create an irreversibleresidual magnetic force with a magnetic air gap energy of at least 6652(line-amp-turn)/cm3; coupling the first element to the second elementdue to the irreversible residual magnetic force; applying ademagnetization current to null at least a portion of the irreversibleresidual magnetic force, and uncoupling the first element from thesecond element in response to applying the demagnetization current tonull at least a portion of the irreversible residual magnetic force andwithout an external force.